>>5Incorrect. It only guarantees you a platform insofar as you cannot be deprived of your basic rights for exercising free speech. No one is OBLIGATED to offer you a platform - a university is not compelled to let you give a speech there, a movie theater is not compelled to show a film you made, etc - as forcing them to do so would infringe on THEIR rights. All "protected speech" means is that the GOVERNMENT cannot restrict it. Criticism of the government is "protected speech", but that does NOT mean that websites are required to give you a platform to criticize the government. What it means is that the government cannot order websites shut down because they provide a platform for criticism of the government.
When we talk about a website or other private institution supporting "free speech", that really has nothing to do with the Constitutional concept, rather it's a policy of tolerating opinions that the owners of the website disagree with.
However, I'd be reluctant to classify a website as being against free speech simply because it bans people for posting pornographic photoshops of someone's wife. At that point it's not really expressing an opinion or view, it's essentially a personal attack that goes against all standards of human decency. At that point, banning it isn't censorship, it's maintaining the quality of posts in a community.