Think of negative feedback towards buyers as a poison pellet. You’re not permitted to poison the buyer… and giving them a nice chocolate presented in a glossy wrapper marked POISON doesn’t make it poisonous. The buyer simply removes the wrapper (asks eBay to remove the negative comment) and blissfully consumes the chocolate (look pleasurably at the comment-less green dot.

Just block the nonpaying buyer, report as NPB, and the resulting invisible strike will frustrate the buyer’s attempts to repeat their behaviour with any seller whose buyer requirements are set to block bids or purchases from any buyer with 2 strikes.