It's hard to say what happened since we haven't heard Forstall's side of the story but maybe then Cook or the board saw the tension between Ive and Forstall camps, and recognized that losing Ive to another company would be devastating. So they set Forstall up to fail by setting him up to get Maps done in two years (or however long they were planning)

Regardless, even if Maps is totally Forstall's fault, they still threw him under the bus with this story.