It's legally safer for Disney to simply refund them, especially if Disney's trying to be more proactive in chasing down scalpers. In most cases, it's hard to tell with 100% certainty that a ticket has been "scalped". If they're wrong - it's a lawsuit waiting to happen, and the refund would be cheaper than fighting it.
Side note for the thread - I don't entirely buy Fit-Bunch-546's story as it's written. They said this:
A sizeable percentage of the tickets that eBay sells are electronic tickets. There are plenty of stories of folks getting refunds via eBay in situations where electronically-transferred tickets were discovered to be invalid or cancelled. And if eBay is willingly cancelling OBB listings, they have to have some indication that those sales are problematic - otherwise, they wouldn't be willing to cancel them.
But, mainly, that buyer needs to follow eBay's policy - ask for a refund from the seller,
then contact eBay,
then contact the payment processor for a refund -
their full story implies they didn't do that. (They just need to do more, period - assuming the story is real. Even another call to eBay would be better than quickly accepting the loss.)