That’s a good point that there are two separate kinds of free speech. One is the legal protections, and one is the idea of speaking to power. But when people complain that their free speech is being infringed, that necessarily means they’re complaining about the legal Freedom of Speech protections.
The latter one, being irreverent and speaking to power, is never guaranteed to be legal nor come without negative consequences or having your platform removed, so if that is the one being referred to, the feigned incredulity about Facebook taking it down is misplaced. It was always going to be taken down or fought against, if you’re going to say something they don’t like. In fact, the act is a provocation who’s goal is to stir the pot. The goal may be to shame or embarrass someone, or it might be to change policy and making things more fair, but a reaction is expected and desired.
For the other kind, legal Freedom of Speech protections, not all speech is protected. So, being incredulous about Facebook removing obscenity is misplaced here too, because removal of some kinds of things is completely within the bounds of Free Speech Protections.
Either way, in both cases, the speech is subject to community guidelines, and some kinds of speech will result in consequences you might not like. In particular, things that might be considered pornographic or obscene.
Note this is different from what Facebook might allow, and as far as I’m concerned they can make whatever rules they like and it doesn’t infringe on “free speech”. I’m making the separate point that Free Speech itself always comes with the same kind of limitations the GP comment was referring to.