My guess is he has multiple npubs with the same handle and profile pic. So when you block one, another finds you. It's most likely someone who wants the spam problem fixed so they are exaggerating the effects to 'encourage' a solution.

I don't see him much on Primal or noStrudel plus, I use a couple of paid relays that may filter him better than I can. When I see him, I mute/block him so I don't always know when he is replying to my notes.