I don't understand your question. Garrett has a QB, though it's looking more and more like not a very good one. But if Dak fails, that doesn't necessarily mean Garrett pushed Dak on the team contrary to what others wanted. Maybe he did, but I think it's much more likely that it was a collective decision, and frankly given that Romo had been injured 3 of the previous 5 times he played and the team had the best record in the NFL with Dak at the time, it wasn't an unreasonable decision.
Ultimately though, it's losing that will cause Garrett to go down, regardless of who is at QB.