He has to be fired because RG3 can never trust the Shanahan's again.
Why ?
Trust is a two way street.
If Griffin has been circumventing Mike & Kyle and getting Dan involved with how he would like the offense ran, then coaches might have lost trust in the Griffin also. Why else would Griffin feel confident enough to disrespect Kyle publicly unless his relationship with Dan was nice and cozy ?
Whether or not you believe the reason Mike gave publicly to shut down Griffin, Mike should have the authority to make that decision.
Mike is not going to say publicly, what I feel is the true reason he decided to start Cousins, that he wanted to see if Griffin would again run to Dan to intervene in the decision. Like spoiled children, Mike is forcing the owner & the QB to both acknowledge the HC is th ultimate authority when it comes to football operations.
Additionally, nothing gets Mike more upset then players who are not prepared. Griffin has been throwing horrible, high-school like, lock-on and read INTs. Griffin's inability to quick-release the ball is also major reason for so many sacks. Mike should have the authority as HC to bench a player if they are not performing. Even if that player is the franchise QB.