He probably couldn't land anywhere laterally for that year.

I imagine he was so disillusioned with the process and didn't want to pack his family up and move them again for a one-year gig at a lesser program (before packing up for another program a year later). A stable job with family that allows you to stay in your home is pretty tempting in that situation.

Loads of reasons why he might not ever get back into coaching. Timing and circumstance are the most likely explanations.