I really don’t even think the votes table would need to itself be federated; it could just be on the user’s instance. Upvote/downvote would be a call, but it should really only require the post or comment ID and voter instance. If an instance spams votes, those upvotes/downvotes could be deleted and the instance defederated
Warrants are required for U.S. Mail. Likewise, the government should not have warrantless access to all electronic communication. It’s an outrageous position.