Probably the best solution would just be a client setting to automatically embed images or not. Banning people like that is just a whack-a-mole game. And nuking an instance over a few bad actors is a good way to harm the fediverse as a whole if done too liberally.

What the fuuck

Can’t you disable direct messages totally? I usually turn those off everywhere.

You pissed off one lonely guy, not a bunch of people. Have fun with this loser or get creative with your blocking. There’s probably some info he’s leaking somewhere, or maybe you already have a username? Go nuts. Reverse username search, send him links, pay for services on the darknet. Why not have fun with your new admirer?