Sorry, but you hear what you want to hear. The faction rally was going to be weeks ago, and the weapons are already in the game's API.
The change came because of all the DLC "locked content" uproar. Plain and simple.
Bungie screws up because they don't communicate this. People were 100% expecting new guns and that's the problem. Bungie can't say why they pulled them, so they say it was all part of the "plan". It wasn't. The faction rally got cancelled and was supposed to happen weeks ago. The loot was ready to go, it was just all COO loot.
https://www.gamespot.com/articles/destiny-2-faction-rally-canceled-as-bungie-reverse/1100-6455587/
People whined, cried entitlement, and the faction rally got postponed and then nerfed. Bungie messes up a lot, but they never planned on having a faction rally with nothing in it.
Had nobody complained, we'd have had a 2nd faction rally with new guns.