I feel very sorry that you had to endure all of that. He was very selfish endangering your life and probably someone else's. he should not have put you through all of that when you were only doing him a favour.
There is not a great deal that you can do about it.
tell him that he was very stupid and dangerous and that he should get used to the bike first and that you thought he was a PR1CK in front of those mates. Make him feel two foot tall.
Then let him learn the hard way and don't go on any rides with him.
I know this sounds harsh but I am concerned about you and other people and not him.
HE WILL LEARN and GOOD LUCK.
