The five Ineffable greatest personalities (The Prophet (SAWA), Imam Ali (AS), Fatima (AS), Imam Hasan (AS) and Imam Husain (AS) have repeatedly said in many authentic Hadeeths that all the nine following Imams are Infallible. Believing in Hadeeth al-Kisa leads definitely to believing that what ever was said by the greatest Five is the absolute truth which is strong evidence that all the twelve Imams are Infallible.
There are two ways to look at this. "Hadith al-Kisa'" can be used for a group of narrations, mostly short narrations, describing the general event in which the Prophet (S) covered Ahl al-Bayt (A) with a cloak and identified them. It is generally agreed that this event took place.
"Hadith al-Kisa'" is also used specifically for the longer narration of this event which is attributed to Fatimah al-Zahra (A) and which is often recited at gatherings today.
I assume your question is about the second one (that is, the longer narration of this attributed to Fatimah al-Zahra (A)).
It is reasonable to say that there are some questions surrounding its chain of narration. However, this does not automatically mean that is fabricated, unless there is evidence or an argument that it was fabricated. There is a big middle ground between "strongly authenticated chain of narration" and "fabricated", and, when dealing with texts that are over a thousand years old, many fall into this middle ground.
(I don't think the "sequence of events" argument is strong enough to declare it as fabricated, since no one today was alive back then to say exactly what the sequence of events was, but everyone is different.)
I would suggest that it is good to appreciate the general meaning of this narration, but not necessarily to hone in on every single word and use every word as absolute proof for the nature of reality, as some people sometimes do sometimes.
For instance, sometimes some people feel disappointed when they are having a personal problem and recite this text in a gathering, but their personal problem is not solved. This is because the text says that whoever recites it will have their problems solved. It is better simply to take that as an expression of hope that Allah might solve their problem, and that, perhaps, by reciting the text sincerely, it might bring them closer to Allah and inspire divine assistance or intercession. (Rather than taking it as a literal guarantee.)
At the same time, today, it has become a sort of customary "requirement" to recite this narration in certain gatherings, and this is also not correct. (If Allah has not required us to do something, who are we to require others to do it, such that we might attack or condemn them if they don't?) It is fine to recite it, or fine to skip it.
Unfortunately we are living in a time where there is a lot of intolerance, some people need things to be absolutely right or wrong, either absolutely correct or fabricated, you either have to recite it all the time or never recite it at all. The reality is, it isn't really possible to apply that standard to much of our textual heritage (apart from the Qur'an) since we are dealing with texts that are over a thousand years old. What can be said is that the text exists, it has become part of the Shi'i custom and perhaps there is a reason for that. There is spiritual merit in reciting it and pondering over it, in any case it should be treated with respect. However if someone chooses to focus on other texts, that is also fine. Either way, they should not be attacked for their decision.
At the end of the day, actions are judged by intentions, and if someone is approaching Allah sincerely in a devotional manner through using a text attributed to Fatimah al-Zahra (A), I am sure that Allah would appreciate that and respond in kind.
Hadith al-Kisaa' is one the most authentic hadiths in both Sunni and Shia books. It is a Mutawatir متواتر Hadith.
The meaning of hadith al-Kisaa' is agreed upon by all the scholars of the science of hadith in both Sunni and Shia schools of thought.
This stage of confirmed authenticity is called tawatur ma'nawi تواتر معنوي which means it has been narrated by most authentic narrators in the same meanings of it.
Umm Salama, the wife of Prophet Muhammad (SAWA), Aisha, Abu Sa'id al-Khudri and many other well known narrators have narrated the incident of the kisa being put by the Prophet (SAWA) on Ali (as), Fatima (as), Hassan (as) and Hussain (as) with him and his dua to Allah (swt) saying "Allahuma haa'ula'i Ahlubayti" which means "Oh Allah, these are my Ahlul Bayt (progeny)".
Hadith al-Kisaa', which is recited in many gatherings of the momineen, is also narrated fromJabir ibn Abdallah Al-Ansari from Lady Fatima (AS) by authentic Shia ulama like Sheikh Abdullah al-Bahrani in his well known book al-'Awalim.
The narration is continuous by authentic narrators until al-Sheikh al-Kulayni who narrated it by continuous change of authentic narrators till Jabir ibn Abdullah al-Ansari. The hadith has been narrated by:
· Shahid al-Shushtari who is well known in India as al-Shahid Salis (Thaalith) in his book Ihqaq al-Haq (vol 2, page 554)
· Al-Turaihi in his book al-Muntakhab
· Sheikh al-Daylami in his book al-Ghurar wal-Durar
· Zain al-Dimishqi al-Hanafi who is a Sunni scholar
A person who tells you that hadith al-Kisaa' does not have a good source of narrators has misunderstood the situation of this Hadith or maybe has less knowledge about Hadith al-Kisaa'.
There are people who create doubt about anything even about Allah (swt) and the Qur'an or the Prophet (SAWA) but we don't care for anyone who creates doubt when they do not have any authentic evidence.
Great ulama have narrated hadith al-Kisaa' and its meaning has been narrated by main Shia and Sunni books of hadith.
Hadith al-Kisaa' in its meaning is the incident of the kisa when the Prophet (pbuh) kept the kisa on Ali (as), Fatima (as), Hassan (as) and Hussain (as), and Jibrail also coming and taking part with them is also narrated by:
· Sheikh al-Tusi in his book al-Amani
· Tafsir al-'Ayyashi
· Tafsir Furat al-Kufi
· Tafsir al-Qummi by Ali ibn Ibrahim
· The book of Sulaym ibn Qays
· Kitab al-Khisal by Sheikh al-Saduq
We need to be careful of those who claim anything against our faith, claiming they have some doubts. Let their doubts remain with them, for them and on them, but they have no right to create doubt among the believers regarding a hadith which is one of the most authentic hadiths.
In Sunni books the hadith al-Kisaa is narrated in its meaning in:
· Sahih Muslim (vol 4, page 1501, hadith no. 2424)
· Musnad Ahmad ibn Hanbal (vol 6, page 292)
· Sunan al-Tirmidhi (hadith no. 3796)
· Al-Mustadrak alaa al-Sahihain by al-Hakim al-Nishapuri (vol 3, page 133)
· Musannaf Ibn Abi Shaybah (vol 6, page 373, hadith nos. 32093, 32094)
· Asbab al-Nuzul by al-Wahidi (page 295)
· Al-Suyuti in al-Durr Al-Manthur (vol 5, page 198)
· Ibn Taymiyyah, the well known enemy of the Ahlul Bayt (as), admitted the authenticity of hadith al-Kisaa' in his book Minhaj al-Sunnah (vol 3 page 4)
You mentioned in your question that the person who told you that hadith al-Kisaa' has no strong source seems to be a scholar. I am sorry to say that he might seem to be a scholar among people who are not scholars but a person who speaks this about hadith al-Kisaa' according to the authentic scholars needs to go and study the authentic sources of Hadith al-Kisaa. He needs to study and research more to know that hadith al-Kisaa' is one of the most authentic hadiths.
The Prophet (SAWA) did not pray to Allah to keep Ahlul Bayt (AS) away from Rijs, but he prayed to Allah to keep the Rijs away from Ahlul Bayt (AS).
This is a misunderstanding in the minds of many who do not realize the difference between (A'nhom) عنهم , and (Minhom) منهم or error in the translation.
A'anhom: means to drive the bad away not to be near them.
Minhom : means to drive the bad from them.
Allah (SWT) never said Minhom, but said A'nhom.
انما يريد الله ليذهب عنكم الرجس أهل البيت ويطهركم تطهيرا (33:33)
Ahlul Bayt (AS) are The Infallible Divine leaders who are completely purified by Allah (SWT) who stated in Quran that He wants to to keep the bad away from them because they have nothing from the bad at all.