you don't have a right not to be shadow banned. it's the best solution to many problems with trolls who will keep coming back on new accounts, with new IP addresses and so on. it's really hard to get shadow banned most places, you have to earn it.
also you don't have a right not to be censored by private companies.
Not that I'm necessarily arguing for GP's point here, but the point of a bill of rights is to grant or in some way codify rights that people think they should have. They are not necessarily lists of natural rights that won't be violated.
when I say that it should be taken to mean "you don't (and are not entitled to)". there are a few bad actors who are persistent and tools like shadow banning are very helpful with that, saying that socialism is awful isn't going to get you shadow banned.
Of course they can. They just can't sell you stuff based on false premises. E.g. selling an ad that won't display because you're shadow banned but you don't know that.
also you don't have a right not to be censored by private companies.