I had someone I had considered a friend who started doing that when he became annoyed with something I posted. I finally told him that if he blocked me again, I was blocking him back—and I don’t unblock. He did, so I did, and that was that. 🙁
it's like a doors song. it's odd to see how people try to entertain themselves. might be worth a block to just not see anymore. or report it... probably easiest to just delete the message and if things go well, they'll fall into the 'requests' box and only be able to send one.