Hey, there. Let me attempt to clear some things up here.
Xur is randomized. There are times when we can pull off miracles like making him stay in the Tower longer when Christmas is cancelled, but his inventory is governed by the same chaos that influences all the loot drops.
Comments in that video about "the plan" were more about the fact that we know what he's selling before he appears, even if we can't reach out and stock his shelves ourselves. We set him in motion, and his will is not his own.
Also in that video, you can hear me confessing that I'm not always in the loop when it comes to these things, so you should take pre-game lobby comments among friends with a grain of salt. That video was from months ago, and I was still learning the intricacies of all the new systems that we launched with the game.
These conspiracy theories are symptoms of a burning desire. Gjallarhorn is the most popular ask that comes my way. I know you want it, even more than the collective requests for more vault space. As you can see, these are things that are beyond my control. I don't have one either.
I'll do my best to talk to the people who create the code that drives Xur, and see if we can make him more valuable to you in the future.