AutoMod is currently missing from both Lemmy and Kbin.
If AutoMod gets baked in to one or the other (or both!) then this sort of thing will go away down. I was a mod on a 500k+ user subreddit and AutoMod did most of the heavy lifting for this stuff.
Obviously it's not acceptable behaviour, but you've got to understand that all the admins and mods here are volunteers, and the platform is still young. That, combined with no automatic spam detection, you unfortunately can't expect an instant reaction to every single troll. They did get banned, roughly 1 hour after your post.
I already got him banned from beehaw. It's going to be a thing that happens since ppl like that are able to join other instances and just post shit like that