I suspect his time at Argyle rammed home to him finally the futility of being the fall guy for a poor budget, miles from home. After all, he's dealing with other self interested people in the football factory, so why shouldn't he.
Get a decent job that pays well, that's near enough that you can travel to on the bus, and see your family all week. That's what most people do. I would think these days 30 years of being a player and manager in pro football should give you enough financial security to pick and choose, as he did down here, when he thought he would rather be jobless than do another season.
I thought he was a miserable soul, and a niggly player, but he's done reasonable jobs wherever he's gone. It doesn't get much more Yorkshire than that.