I don't think it's politics. Rosen himself has said he likes to question everything. McD preaches team before self. I don't see him wanting his QB to be a guy that openly challenges everything. It isn't about Rosen, McD, it's about team.
Look up "Rosen Time" McD would never tolerate a guy with that attitude. I wanted Rosen, heck I think he is the best passer I just don't see a way in which McD goes for it.