Blacklisted by PayPal yes. But who cares. They are a ruthless company only interested in filling their pockets. It'll have no ramifications outside that.
It's either that or lose the money. So I would suggest unlinking anything with PayPal. Once a chargeback is filed the account is frozen.
Are you sure? I'm pretty certain that there's some way to go through the small claims court to get the money back. And a judge would not look favourably on someone doing all they can to avoid it.
His fault for not sending it recorded post. His responsibility if it doesn't get there. His responsibility to prove it did get there if the buyer says it didn't.
I'm not trying to be unsympathetic, but it's not right to try to do a runner with the money.