I think he also knows that he can't dick Cohen around and say, coach a game or two for old times sake if he felt like it.
In fact, Raffo is probably the only coach in America that would let Polk do that, and I'm sure that whenever Polk wanted a favor, he could conveniently remind Raffo that the job would not be his if it weren't for him. I'm still waiting to see if Polk ends up at ASU with him, and if I was Raffo, I would cut at least the direct ties for a little while.
I do think that Polk was trying to protect his assistants and his players to a degree, as well. He knew that by retiring, unless MSU named Raffo or McNickle the new HC, his staff would probably be out of a job- and he also knew that their next jobs wouldn't be at a place like MSU. And when you get a new staff, promises that were made during recruiting go out the window, which in a sport where making millions is possibly at stake, at least in most of the parents minds, even if their son is a walk-on second baseman, that's a big deal. There's also the possiblity that the players could get cut- including some of Polk's favorites.
One interesting thing that I noticed is that during the LONG period between Polk's retirement and Cohen's hiring is that Polk mentioned that Raffo would be different. That tells me that Polk knew what the fans wanted and wouldn't do it.
