He does think so, because there's no way Jake could be a ghost. He's refusing to believe it. If he does turn out to be dead, then Cougar will take on a course of vengeance, but they're missing pieces to prove that Jake is actually anything more than impacted.

Cougar glances at the cave on the map, grimacing and staying away from it, crossing his arms over his chest. "Next time, no touching anything without me around," he warns, because there will be a next time, as far as he's concerned.