Benching him for a series or possibly the rest of the first half makes the point. Benching him for the game shows immaturity on Gailey's part. Seems it was a vain struggle to grab some control of the team, which he has clearly lost. This will only push players further away.
As GG said, look at the problems Gailey had in Dallas with Aikman, etc. The old man thinks he's above the players, and in today's NFL the coach isn't. (with a few rare exceptions)
The only "lesson" that Gailey showed was that he's willing to put winning on the back burner. That attitude will NOT endear him to the players nor will it make players want to stay/come here.