eBay's Simple Delivery Help page states:-
'You'll be protected if the item is lost or damaged from the point the item is scanned into the carrier's delivery network and until it's marked as delivered.'
But there is no way to guarantee that a dodgy buyer won't claim the item was stolen from their porch, or safe place. Or they can claim the item is damaged/not as described. With Simple Delivery, eBay cover the refund - but the buyer doesn't have to return the item, so you have no real proof that the buyer didn't falsify the claim.
Personally, I would probably have done the same as you, and contacted the buyer - just to try & get some idea of what they were like, rather than send the item 'into the void'...
