KF runs on old internet rules. There's not a uniform political opinion here, but the deal is that you just put up with the stuff you don't like, because that's how the internet always was. Don't like the gamer word? Well it's used here and if you can't put up with it, go somewhere else.
What you've got to realise is pulling Bella up on this is merely adopting the tactics used by many of our lolcows - performative pearl clutching. Whether or not you disapprove of racism, anti-semitism, homophobia, transphobia or ableism is irrelevant. The rules of the game irl are that those slurs are unacceptable, and it's a suitable cudgel to beat people with (especially zoomers). You'll see this sort of shit on Twitter all the time - "How dare you say Chris-Chan raped his mother. Respect for trans identities is never conditional! Christine raped her mother!". It goes both ways - if polite society sets a standard, then you can tell off someone for yelling at gross fat neckbeards for using fat as an insult because it's invalidating brave HAES warriors who are a marginalised group, whether or not you actually care that fat is being used as an insult.