We need to nominate a dude to the mod team for the EXPRESS purpose of banning this weirdo's alts. I'm grateful to u/DomitiusofMassilia for popping in every few days, but sadly that's not frequent enough. We need a daily reader who can just hit "ban" when he's browsing comments. It won't solve the problem but it'll alleviate it.
We could also freeze new account creation and open it for select periods, announced with pinned posts. Our growth would be disrupted of course, but it's not like that matters that much.
Asking for a person to dedicate their entire life to stalking and banning some random pajeet 24/7 is a bit much.
Are you volunteering?
Eh, I did something like that once on an old mmo php board when it started to get flooded with spam accounts, it helps things but does take some time. I assume here would be a far simpler process, however since all the the accounts in question are from other boards it's not like there will be a list to check for KiA2.win because it's "global".win accounts joining KiA2 to spam rather than being made here specifically. We're it the latter it would be easy to have some sort of gatekeeping setup like for other more spambot like issues, however the situation being what it is likely means a far more hands on approach is needed.