no good deed goes unpunished

I was riding north from Golden through Arvada to do tempo around the Koppenberg circuit.    On Quaker a Land Rover going the opposite direction stopped abruptly and shouted some question.  It was too windy to hear, so I decide to do the nice thing and pull around to see if I could help.  Since he was stopped in the middle of the road, I decided to make a U and pull up on his passenger side for safety.    As I'm crossing his stern (about 1-2 car lengths back) he suddently puts it in reverse and hits the gas.