Shaykh Dr Zaid Alsalami is an Iraqi born scholar, raised in Australia. He obtained a BA from Al-Mustafa University, Qom, and an MA from the Islamic College in London. He also obtained a PhD from ANU, Canberra. He has written and translated several Islamic texts and also prepared educational videos on Islamic rulings and practices.
There is no shar'i problem with praying while wearing a t-shirt or half sleeve shirt.
And Allah knows best.