Well, I mean, yeah?
I think if your ToS allows you kick people off your platform for speech you find disagreeable it should be in violation of the 1st Amendment
The only thing that needs to be curtailed are calls to violence, otherwise it should all be free to say. The only reason we're able to shut people up on either side is because we let them talk then debate them into irrelevance.
the 1st amendment doesn't ever apply to private persons or organizations. it just applies to the federal government (and state governments, but only because the supreme court decided that it should)
of course, it goes against the principles of the first amendment, that much is fair enough