It technically can help believability, but they did not establish this rule of the universe in-game. There was no example or visual evidence of this possibility in game, and even though it's established in the novel, the novel still has the entire structure more or less intact for much of this to take place. Even if they had established the ability for the phase out bit in-game to set the player expectation and the rules of the universe, the fact that the light bridge itself and everything around it got nuked seems to imply that any power source would end up going with it, blinking them right back into this standard dimension. Or if not, how are they supposed to phase back out?

This final question is strictly there to point out that, even though there could be many, many sci-fi plausible answers for how they'd phase back out or how the power source could be maintained, there's still no precedent for it in-book or in-game to back any of it up. Or as you said, Vagueness, it doesn't help believability at all, and as I've said, utterly destroys suspension of disbelief at the time it occurs.