Except it doesn't matter if it's right, wrong, or indifferent...it's whatever Disney wants it to be. An annual pass is strictly a TOS including the grant for park admission and additional benefits in exchange for monetary compensation and abiding by the TOS henceforth agreed upon. If these people are buying things with their annual pass discount, turning around and reselling them to make profit that violates TOS. Point being that you can't agree to TOS and then retroactively reject those terms. Anyways, this is the only way to combat people buying LE souvenirs in bulk without it affecting anyone, other than flippers. That's why your last question doesn't hold up.
They don't care if you bought a LE item from 20 years ago and are reselling it. They care that the flipper walked in yesterday, purchased 30 brand-new popcorn buckets, used their annual pass discount, and then put them on Ebay that afternoon for $20 more than what they paid. Oh and 20 other flippers just did the same thing, so Disney is all out and now they're having to deal with the fallout of not having their advertised merchandise. That's why Disney is ultimately doing this, because it "ruins vacations."