Here is the problem though: The platform of platforms, then, is politics, if we want to keep biology out of the picture.
And the thing with politics these days is, that the state, as a system, is compulsive. I cannot leave the state, I am not free to do so.
In other words, the most underlying platform is not of my choice and therefore it is not as simple as you are making it out to be.
I like your thinking framework and agree with it.
"We don't want your sort on our platform because reasons" ought to be concerning at a much wider level (and not just to the sort that apparently aren't wanted on the platform).
We can all think of things we would ban if we ran hosting providers. We all know there's a line. Why are we pretending there isn't?
"Bigoted messages"? Would that be content that's
* against the law
and/or
* against the upstream AUP/TOS
and/or
* "someone said something that offended someone else"
>> that have gotten people killed
Not wishing to pour more gasoline on the raging fire, but ... source?
This sounds simple, until you realise the requirements aren't well-defined, or that the definitions can be changed arbitrarily (and retroactively) by the platforms.