Because of the weakness of their justification, this could be further gasoline on the fire for his 74 million supporters. I frequently find myself having to argue with said supporters, and I can't argue that this justification makes sense other than to say... well they should have banned him before hand.
It feels like they were looking for almost anything remotely shitty that Trump said to ban him. More specifically, they are looking for a reason to ban him based on saying anything not in support of the next administration, because of his supporters storming the capital. I can see the chain of logic here, I just think it's a little weak and being selectively enforced.
Edited: to make more sense hopefully.