It was actually our CEO who pulled the trigger, but I suspect Gute will be in charge of the next guy and lay down a hard line too though.
The way I saw it, Murphy was either going to announce that MM was gone at the end of season, or possibly fire him before it was up. He probably figured even if winning would do nothing at this point, he still knows Gute and the new HC need to see which of Ted's players are worth keeping going forward. Firing MM may have been the best way to do that as well as letting potential candidates know their dream job of working with Rodgers is now open.