It’s still censorship, it’s just not a form of censorship that 1A rights bear upon.
No. The constitution limits government powers (among those powers limited is the power to ban PUBLIC speech), not private companies (private speech is on you), nor does it protect people from themselves. Else you have totally misconstrued the meaning of the 1st Amendment, and allowed a company to assume power over you as well as where and when you chose to speak.
Just go somewhere else: start your own company or blog, write a book, whatever. Why do you imagine this forum has moderators/admins? They strike posts that are out of line or break some rule posters have previously agreed to - that is not censorship; it is YOU receiving a consequence for breaking the agreement with this site. If you get banned that is not cause to sue ... same for faceless book and the rest.
This site does not collect or sell our info, but if it did and we signed up, then we signed up for whatever they decide to do with it. Should they say you cannot say such and such (whether you fervently believe your speech or not), they can ban it according to the terms you agreed on, and not likening them or the actions as a result are free to go elsewhere.
This is not a Constitutional issue, no mater how much you wish it. It a personal choice issue.
Sure it’s censorship. So is a Christian bakery refusing to make a Sodomite wedding cake.