Kind of splitting hairs, but Osiris says guardians can't be simulated by the vex, which I agree would be because of the travelers light. But a warmind couldn't be simulated by the vex either, which is why it took a warmind to save shin and the gang from the vex simulation. That said, if you decided to expand this theory that Rasputin couldn't simulate the traveler, all that means is that Rasputin couldn't predict what the traveler would do. That doesn't mean Rasputin couldn't see the results the traveler had on humanity and decide that was better than what we had without the traveler. So with that, if Rasputin couldn't predict the travelers actions, then it would make even more sense that Rasputin would have waited until it actually saw the traveler leaving before attacking. Otherwise Rasputin would have no idea. And lastly, I put a little more belief in the TDB/HoW/TTK grimoire. Some of the vanilla grimoire is hard to tell if some of the older story elements still remained or not. Edit: I still agree with your original post 100%