The point you're missing is that when you use a term like that, it's not jiw you see it, or meant it, it's how the person it's aimed at sees it as a result of the context in which it's used elsewhere. In exactly the same way, from my perspective, Remoaner is just a concatenation designed to signify a person that voted Remain and can't or won't accept that they lost the referendum.
I can see how Remoaner could be perceived a mildly disparaging, but if you'd been on tne receiving end of the litany of insults I have, usually couched as &%*€#% Brexiteer, and accompanied by accusations of being a far-right nutjob, a racist, an idiot that doesn't understand the issues, someone that wants to close the door, an isolationist, i migeant-hater, etc, and the barrage of insult and intimidation no doubt designed to belittle, maybe you would understand.
In an ideal world, or forum, neither term would be used. Yet, you continue, and add in claims of how it undermines democracy, is bullying, etc, in the same sentence or post.
How this comes across is that Remoaner is unacceptable because you find it offensive, but Brexiteer is fine because, despite having had it explained, you either don't understand it, or don't agree. Of course you don't, if you haven't been on the receiving end.
And it's not just Brexiteer. That's just the latest incarnation of the cascade of insults anyone with a eurosceptic viewpoint has had for years, decades even, from some europhiles.
And .... I'm not sure any mods do find it offensive, or Remoaner either for that matter. But speaking with a past hat on, if it erupts like it has they have to look at both sides.
My suggestion is that if we can't agree that perceived offense depends on perception, which is coloured ny experience, how about avoiding BOTH.
It seems daft, over something pathetic, but the solution is obvious. Use Leaver and Remainer, and try to stick to respectful arguments, not borderline attacks which, if not intended to provoke, certainly have that effect.