Ghaul was unique amongst the Cabal in that, instead of seeking to conquer the Traveler & seize its power by force, he at first legitimately sought to study its esoteric motivations & prove himself & by extension his species worthy of it.
The fact the Traveler only broke the Cabal cage encircling it AFTER Ghaul stole the Light & tried to affected a corrupted form of resurrection after his initial defeat is very interesting for 3 reasons.
One, it implies the Traveler was not in fact helpless at all & could have broken free at any point. Two, it only chose to break free at that specific moment. And three, it means it was very likely the Traveler was TESTING Ghaul’s worthiness as a potential Lightbearer.
There’s no hard proof that this was the case of course, but considering its subsequent revival of Savathun & motivations thereof, I believe it’s a very good possibility considering the evidence.
Among Cabal, Ghaul was their aspiration…strong, cunning, disciplined, inspirational & brutal when necessary but philosophical when appropriate. If there was ever to be a Cabal Guardian, I truly believe he would have been the first.
And while the Traveler did not engineer or anticipate the Red War, I believe it saw potential in Ghaul the way it subsequently did with Savathun and, instead of simply shaking off the cage, it chose to play at being helpless out of curiosity to see just what Ghaul’s true intentions & character was while assessing his worthiness.
In the end though, I believe Ghaul failed that test when he finally cast aside his principled stance out of anger & frustration to attempt to take the Light by force. And when the Traveler saw the depths of his arrogance in his flawed resurrection even after his defeat by the Guardian, it saw all it needed to see which is why I believe it chose that moment to shatter its bindings & annihilate him for good.
So now to the more interesting question…what if Ghaul HADN’T abandoned his principles in a fit of anger at the last moment? What if, upon seeing the approaching confrontation w/ the Guardian, he once again rebuffed the Consul’s rash advice and, coming to a realization about the Speaker’s words about sacrifice, chose to fight us on his own terms & died with honor after a hard fight?
If this scenario had played out, I truly believe that after some time had passed in the smoldering aftermath, a lone Ghost would have appeared & raised Ghaul as a Lightbearer as he would have passed the final test: devotion leads to sacrifice.
Confused & with no knowledge of his past, who could say what would have come next for him?