Agreed. I believe the terms were that the automatic renewal provision would no longer be triggered, but I don't remember any provision saying that the AD has the right to unilaterally fire someone on KF's staff. BF reported to the AD for HR purposes, but staffing decisions are almost always left to the HC at Iowa and any other university. KF's 24 years gives him even more leeway than most.
The AD will not fire Brian. KF will not fire Brian. Assuming KF decides to come back, there will be a mutual and professional parting of the ways where BF leaves for another lateral coaching opportunity.
That said, if KF digs in his heals and says BF returns, what really would anyone do? Grumble. That's it. This is KF's world and we are all just living in it, especially if he wins a few more games.