Sayyed Muhammad Husaini Ragheb, Sayyed Muhammad Husaini Ragheb has a BA in Law from Guilan University, Iran and has also undertaken Hawzah studies in Qom. He is a Cultural Affairs director of Ethics Group of Al-Mustafa Open... Answer updated 10 months ago

Salam
Ruling 630. Exhuming the grave of a believer – i.e. opening his grave – is unlawful, even if the grave belongs to a child or to an insane person. However, there is no problem if the body has completely decomposed and has become dust.

So the reason mentioned in the question is not a necessity to justify the exhumation

To know more about the exhumation and its exceptions visit:
https://www.sistani.org/english/book/48/2189/