I actually do see where Kirk is coming from, he's been on the job for 25 years, outside mettling is uncalled for when you see his track record. Iowa is still firmly in the conversation every year. The Big Ten has gotten incredibly defense oriented over the last 5-10 years, it's not like he's got the only team not scoring a bunch of points.
The problem with hiring family, especially in a (overpaid) role at a public institution, is that the scrutiny is going to be far more intense.
At this point in his career, he might not want to start over with a new staff, a realigned conference and nothing to gain while risking his strong legacy.
He can start Ferentz & Sons Investments, LLC with all of his earnings and stack the board with his progeny.