The entire Athletic Department is currently being reviewed. This whole situation could be a massive dumpster fire for a little while.
What coach is going to take that job without knowing who their boss will be (I foresee a new AD soon)? What coach is going to walk into that with an interim University president who can't offer any assurances on what comes next? What coach is going to take that job without knowing what the ramifications on the program will be (I mean, besides the NCAA slapping them on the wrist and extending Harbaugh's exile from college football - because they still hate him)?
Whomever Michigan is targeting will be lined up for 2027, assuming they can clean up the mess before then. I believe Poggi will get the gig for a year - similar to how the U handled Claeys (although I expect Poggi will be clear on what the situation is, and it's likely Michigan's new AD will be able to communicate, have a spine, and handle the transition with class).
They have no intention of keeping him, but will lean on him to get them to a place where the new president and AD are in place, all parties understand the landscape, and there are enough zeros at the end of the salary (I'll guess at least seven zeros).
Michigan is a mess right now, but they won't make a panic hire. Quite frankly, they're lucky Biff is in place. He's the only chance they have to hold this together until they can get the hire they want in place.