We don't need to depend on federated downvotes to judge what does or does not belong on kbin. In fact, I think it's probably better if we don't. People are downvoting the bots here. I have yet to see an account with negative rep. on kbin that wasn't a spammer.
Regardless, rate-limiting incoming posts will limit the damage and annoyance to us.
I wonder if there needs to be some kind of "governance board," like the NATO or EU of the fediverse, where major instance admins meet and set agreed upon standards of instance behavior.
I'm not sure that would help with this particular issue -- and there's already a fair amount of bad relations between instances so I don't think a wider fediverse board is likely to succeed even if it could help somehow... I guess instance admins that do agree on general moderation principles could help co-admin each other's instances to cover better for when they're offline (maybe some of them already do?), but we shouldn't have to depend on remote admins being responsive to deal with an issue affecting our instance.