Yeah that could happen, I mean he did fight the "Flame Emperor Sabo" with the Fire Fruit and yet has no permanent or at least ongoing injuries too from it, despite his major weakness against fire too ofc. It would be very surprising if he's more resilient to fire than we expect, able to tank more than we expect at least.
That is possible, maybe Green Bull has his own agendas too but he's gonna wait until he encounters Luffy to really express them, at least in a partial way ofc. He needs to meet him and see him for himself, make his own judgements and such.
I really hope there is more nuance to Green Bull and we even see more of his jollier side from the Reverie somehow. Fujitora was a real wildcard character and I hope for the same on a fellow new Admiral with Bull in his name too especially.
I can def see him being saved for a final confrontation in the final war too, definitely.