Restrict the number of accounts that can join that family group. And/or remove the ability to share the library from the main account for repeated offenses.
Or require multiple family members accounts to have to cheat before the owner account is banned.
I think he should be tried for treason. And if convicted suffer the full punishment for that. He is a clear and present threat to democracy. No one should be able to invite an insurrection and have it not be taken as seriously as it was.