I don't think Bo promises anything to anyone........but he is a good guy, and thus he is not going to let Watson's career go down the tubes.
Let's face it..........Watson put a lot of work into (trying to) help our team win games...........he just wasn't the right fit. It's easy for us to criticize him for being a dumbshit, but in reality, Watson is just a NFL style coach.
Gus Malzahn came straight out of HS when Nutt brought him on as OC, I think he's doing pretty well so far. Pulling coaches from HS's can bring a twist to a new offensive scheme as well. I think it's a pretty good move, time will tell.