New Guy this is yet another sad commentary of agents behaving badly. This listing agent is actively soliciting your friend.
So in the face of this behavior would your friend honestly want this person representing him/her? Would your friend trust that representation? I would ask your friend to contact the listing agents broker and explain exactly what happened. Also when the original purchase offer was declined did your friend get a copy of the RPA back from the listing agent as officially declined?
I cannot advise strongly enough to your friend not to use the listing agent to represent him as well. If your friend wants the house, have him ask his buddy (agent friend) to represent him to give him a rebate of a portion of the buyers commission OR to reduce the buyers commission paid out to him and have the price of the home reduced. Or go to ZIP or other brokerages that give commission rebates and use them.