Eric Bieniemy is a great coach and offensive mind. But he has very very limited college experience, most recently a full decade ago.
Just as there's a transition going college to NFL (some can make it like Carroll, some can't like Saban, Chip Kelly or apparently Urban), there's a risk in going NFL to college. The practices are different, the players are different, and recruiting is suddenly half the battle.
That's not to say that Bieniemy wouldn't be a great fit, just to say that there's some risks involved and I can't see them going overboard to get him when they have other strong candidates (Fickell, Franklin, Peterson, even Sitake) who have college experience. Peterson, in particular, would be a guy I'd take over Bieniemy if I was committed to paying an absurd amount to pull someone in.