I don't think it is as simple as it sounds.
Callahan was not going to fire Cosgrove, they were college roommates. I think it was a deal breaker, he was willing to quit or be fired before he fired his buddy. Also, he was disrespectful of Osborne, which helped turn the fanbase against him more. And I don't think TO liked his brand of football. So when TO took over from Pederson, the writing was on the wall.
Pelini could not handle the pressure of being the Nebraska head coach. I doubt a life coach could have changed that. Hell, he couldn't handle the pressure of being the coach of Youngstown. And his disrespect for the UNL administration was ingrained and could probably not be changed. Getting the innovation campus going was critical to Perlman and when he bought potential investors out, having a raving lunatic on the sidelines didn't promote the NU brand very well.
It's like asking how about keeping Frost if he were willing to bench his starting QB and hire a new OL and QB coach? He isn't going to do those things, so the point is moot.