Generally speaking, users flag posts, not mods. I have seen that some posts are minimized on load, which I believe is done by mods; that doesn't appear to be what happened here. A bunch of people thought it was inflammatory (or disagreeable, or controversial, or whatever) enough to flag it.
I'm pretty sure he's fully aware it's BS. He's also the guy who censored journlists and acrivits Twitter account on day 1 when he bought the company, and also the guy who canceled a command for a Tesla by a customer after a bad review.
Musk gives no shit to free speech, it's just a rhetorical argument, which isn't unheard of: https://i.redd.it/3b470c0htra61.jpg (note that I'm obviously not comparing Musk to Hitler here…)
in fairness its not entirely false - at some point he started talking about how it is banned and considered a slur on twitter... but nothing came of it and like all other slurs it continues to be allowed
i do, and i was agreeing with the case that it is not false (ie the ban is not entirely false, because he said it). then i said you can use it, just like any other slur, but i imagine it will get flagged
i imagine the confusion here is that you're making the case that cisgender is not a slur