Just a heads up, this person is a known troll across lemmy they’re well known for their hostile and inflammatory content and just saying things to get a rise out of people, this person also isn’t exactly receptive to feedback. Just wanted to let you know since trying to talk with someone like this is like talking to a brick wall.
Vote manipulation will be tricky to enforce, since votes can come from any Instance due to the whole federation thing, if the user uses the same username on their account it’s easy but if not it can be very difficult if not impossible.