Allama majlisi in Mirat ul Uqool, Vol 20, p42 says:
Ḥasan.
I say: These two reports do not prove the occurrence of the marriage of Umm Kulthūm (may Allah be pleased with her) to that accursed hypocrite. Rather, they were due to compulsion and dissimulation (taqiyyah). And in some narrations we find what contradicts it.
Alkarbala