Some thoughts on Bad People on the Interwebs. There will always be such people, and I think the best policy is just to block them or delete their accounts if they go against ToS and/or CoC.

Trying to escalate to ISPs or legal entities is likely to bring trouble into the fediverse and unless you're upper middle class the legal entities are not going to want to help you and may take it as an opportunity to do the opposite by applying heavy handed methods.