Yeah I don't buy "control" being an issue. What control does Gruden want that Hart won't give up? Hiring and firing? I guarantee if Gruden says "I want to fire so-and-so" or "I want to hire so-and-so" then Hart would do it no question! That's silly to think otherwise. The kind of control that NFL Head Coaches often desire (GM control) is not something that a college coach would want.
The hold up is probably about the language of the contract. I'm sure UT wants to protect themselves if Gruden decides he hates college and wants to take an NFL job, probably a big buyout. Gruden obviously will want the freedom to move on if he so chooses without extreme penalty. Here's the thing he doesn't HAVE to take a job, he will make 4.5 million sitting in a booth calling games. UT has very little leverage in these negotiations. I doubt he will lose sleep if he passes on the UT job so if UT truly wants him, they better make it worth his while. They don't have to cave to all his demands, but he has to have some motivation.
If I'm Dave Hart I give Gruden everything he wants in terms of salary, staff, and control (still not sure what that means though). I come up with a reasonable and negotiable buyout if he decides he wants to move on. If Gruden truly wants the job he will accept something like that, but if he's going to be crazy greedy then there's no point pursuing him further.