Everybody is a unique individual, and there's no reason to compare Heup to Mullin. That said, Dan Mullin is a much smarter and more capable man than Billy Napier. It is what it is. Coaches get paid way way way way too much and they have a difficult personal life and it's in their best interest, always, to be fired.
Better to look at Heup and realize that he personally is already huge mess. Physically he just looks terrible. Managing the roster is way more work than it used to be. Mentally, who knows where he is, but he's not a guy who gets razor sharp in the last 2 minutes of a close game. He's not that. His contract incentivizes him to get fired above all else. His life will be way worse if he stays on the job. Worry about that. If he pulls his personal self together I think that's probably the best thing that can happen to UT football. I don't know the guy.