Perhaps, but you're referring to simulations you know about. The Vex are very mysterious and we know little about them. Their simulations could be very different from the ones you know. For example, when the Spire builds completely, it emits a beam of light towards the entrance of the Vault. For all we know, when this happens, it could activate some sort of emitters or gas that forces Guardians into the simulation. Again, this is all speculation. You could be right, as I said, this theory does have its fallacies. Thanks for the input!