I dunno. Its as plausible as many of the other theories in here.
Gruden loves UT, wife a cheerleader, etc, right?
What if the AD knew he wasnt interested, and knew many of the fans and boosters would be upset unless a run was made at him?
In that case, it could be useful to have him run interference to make the appearance that youre going after him. Enthusiastic pocket books open up. At the point you have your coach locked up, Gruden announces hes declining the job. You then have proof offer was made, and you tried to lay out the big bucks and go after the hire many wanted, you get the benefit of motivated boosters, and can wrap up the candidate you wanted without having Volnation sniffing out the deal and wondering why you werent going after Gruden anyway. So many have said as long as they show theyre willing to try, Ill be happy; make him say no, etc. In this scenario, everybody wins, except those that only wanted Gruden (who in this hypothetical was never an option anyway).
Edit: to extrapolate further, I presume it can be very damaging for an AD to appear to make multiple offers and strike out (as is often the case). If the fan base is in such a frenzy over Gruden, no one is listening to the noise they dont want to hear (ie UT interested in -insert non Gruden name here). That could make someone like Gruden a valuable deception commodity.