It's true. You're not losing anything by ignoring him because you won the moment you put him on blacklist. If he wants to spend his days as a ghost hovering over your FC then that's his questionable decision.

Unless you confront a GM about it personally you will probably get no real response from them. I had an FC member once that would report strangers because they would hover over our FC house for too long. Some of them were just trying to be legitimately friendly too. I could imagine that if there other people who report for frivolous things such as that, most reports aren't glanced at a second time.