Since all of the loot is generated (seemingly) server-side at the time it's dropped, there's no reason why they shouldn't be able to just drop Year 1 exotics/gear for non-TTK players. (No surface reason I can think of, anyway; maybe it's unworkable in the code or something.) And it's the way of MMOs (and pretender MMOs like Destiny) to have the trash loot in the expansion be better than the best of the best from the base game. It's like finding some nothing rusted sword in the first WoW expansion that's better than some flaming, gilded sword from the original game's highest level dungeon. :D