Data is physical. Prove me wrong.
A better argument would probably focus on the durability of data rather than physicality of data, (particularly the private key and any other data that is needed to access and spend the unspent outputs.) We've all been around enough to know what happens to people that lose this particular data. Yes, the data of the unspent outputs still reside on every stored copy of the blockchain, but that means fuck all if don't have the data you need to spend them.