I really don't confront dufus cagers. My initial reaction is to get pissed off, and that just isn't the time to have a confrontation. If an apology was offered immediately, that would difuse the situation, and all would be good. But if the cager is some arrogant ******** (of which there are plenty), then the situation could quickly take a different turn and get out of control.
I'm better off just chewing the inside of my mouth, yelling a few obcenities inside my helmet and waiting for the adrenaline rush to subside.