Buyer Claims They Came Home To An Empty Package

A buyer messaged me "it comes like this" and just sent a photo of an empty polymailer on their doorstep. I was suspicious because who steals a t-shirt and just leaves a polymailer behind in broad daylight, it's very odd. Like at least they would take the polymailer with them. I also know USPS wouldnt deliver an empty polymailer. I figured the Etsy purchase protection would have me covered, so I told the customer to open a help request and escalate it to Etsy. Usually they close them immediately and everyone is happy and keeps their funds.

This time I had some strange mediation team person who just did not understand the situation and first said the buyer did not receive the order in its entirety, then after I explained the situation they just closed the case and refunded them. The refund reason was "item arrived damage" and they said "Due to the nature of certain items, we have limited case mediation capabilities to evaluate the condition of the item when it was listed compared to when it was received.".

I'm just confused, how can Etsy possibly not protect the seller in this situation?