Why would they discount the films on the exact day of the panel if there wasn’t something related to home media whatsoever? It’s not like most iTunes shoppers would know about the convention and connection otherwise…
They talked about the Convention on GMA, the average person knows about Celebration and are now thinking “maybe I should buy those movies, oh look, they’re on sale!” It’s not like Apple needs to get rid of the digital inventory.
And they’re $5 off the whole set. The saga isn’t in impulse buy territory.