I'm reading this more as he liked playing and coaching under Rossi and is valuing that more for his career at the moment. He just lost his job in the NFL, and needs a landing spot and his options were "familiar place, new manager" or "new place, familiar manager". If I had good rapport with a particular manager and was newly looking for a job and said manager had an opening that fit my skill set, I'd probably take that job over a similar job back at a company I used to work for.
If the Gophers have an Open DC position in the future and WDIII is hired as a DC for another P4 program that same year, then I'd feel a tad more upset.