Is it permissible to pray behind a Maliki individual who follows an uncommon opinion regarding the ruling on removing impurity, believing it to be sunnah, especially since he suffers from incontinence and followed a fatwa from a shaykh of another madhhab that relieved him from hardship?

The adopted and well-known position among the Malikis is that whoever prays with impurity intentionally, their prayer is invalid and must be repeated perpetually. As for one who prays with impurity out of forgetfulness or inability to remove it, they must repeat the prayer within its prescribed time. The purity of the worshipper's body and clothes is a condition for the validity of prayer. As for an Imam who suffers from سلس (incontinence), his imamate is valid for those like him, but not for others according to the Hanbalis. However, it is permissible according to the Shafi'is and Malikis, though disliked. The Maliki school's view on سلس is the easiest, as it does not invalidate ablution if it is continuous throughout most or all of the time, and they do not consider it obligatory to purify oneself from impurity caused by recurrent حدث (minor ritual impurity).