To me, the below section confirms that Grier wanted a guarantee he would be the starter. Grier came to Coach Macs office, wanting a guarantee he'd start. Coach told him, you're a gator and your on the team. If you want to start, earn it. A few weeks later, Grier's still complaining so they part ways.
From the B/R article, "I said, the exact quote, "I just want to know what your plans are for the future. Are you going to bring in more guys? Am I a guy you don't see playing here in the future?"
He said, "You're welcome here in the future, you're a Gator, but I'm not telling you my plans. I'm not giving you any guarantees."
Two weeks later, I decided to have one more meeting, man-to-man, and ask McElwain what the future held. I kept asking him what I could do to make it work there. He finally ended up saying, "Maybe a fresh start isn't the worst thing." He said that, and I said, "So I guess that's the move."
A lot can happen during the "he finally ended up saying". This infers Mac booted him, but it could be Grier quits and Mac says, "a fresh start isn't the worst thing"
Mac still looks like a smug donkey though.