Quip or not, he does the ghosty thing anyway. After 76 worms his way in through the metal plates and starts climb, he disintegrates into a wispy streak, making a quick but full sweep of the room before flying up after 76. Seems this is their only exit.

It's unsure about how much room they'll have up here for the both of them, but he can at least stay in this form for a few seconds longer to figure that out. From what he could see below, the hole in the ceiling is past the grated ceiling, so everything is just a guess until he gets in there. It could be just a small tunnel for all he knows. Most ventilation shafts are.