I agree it happens. He could however have refused the reroute. I have been rerouted illegally and told crew tracking it was not legal. They have removed us from the reroute in those situations most of the time. Some reroutes are a gray area and in that case fly now and grieve later applies. In one case they insisted we fly a reroute I felt was improper and it rained money on us. Copilots said we would never get paid. When the settlement came through the copilots promised I drink free for life on trips with either of them!