Censorship affects everyone. It might start small. Yes it's only a little joke, so why not just remove it, right? But before long, you'll have thousands of people shouting to remove half your game because there's something in it that they found "offensive". And who exactly decides that it's "dumb and vulgar"? You? Well what if someone disagrees, what if someone doesn't find anything wrong at all in that joke? Or even worse, finds it funny.
That would be absurd, but it is not a thing that actually happens, because, well, it would be absurd. If somebody went to Obsidian going "You should remove maces from the game! I find maces offensive! Somebody killed my wife with a mace!", that would not result in the removal of maces from the game, even though that person might reasonably claim that the presence of maces makes them uncomfortable. Maces are a part of the game, and removing them is not a thing that is going to happen - and in that case, maybe PoE just isn't for that person.
Racism or transmisogyny in backer comments is not in any way like that in more than one way - it contributes nothing to the game, while making whole swaths of people feel unwelcome. Going from there to "but then you'll have people wanting you to censor EVERYTHING!" is silly.
(And who decides what is "offensive"? Well, really, everybody for themselves - but if there's a lot of people who find something offensive, often because it causes or reinforces violent behaviour towards them or their peers, it's common courtesy not do do it. As a fairly harmless example, I tend to swear a lot when driving alone, but I try not to say "****" &c around children, because that makes people upset. It costs me nothing, and improves life for everybody, including me.)