Of course there's no shame in taking the SAG wagon and none will fault your friend.
Let me ask this... is the AIDS ride more about raising money and awarenes... vs. "You must make the entire distance"?
It is like the MS150... where SAG wagons are full and around you at all times?
I went into my first MS150 with poor training, and pain in my kness. Unfortunately, I wasn't sure how much I needed to train... but the little training I did... I was mashing my pedals.
So, my first MS150 was a MS65. But it was fine. I took a SAG wagon. I still raised the money and that is what mattered.
If this is the case with the AIDS ride... then why not back off your friend a little... reality will hit him when he starts riding. Why not help him raise money for a good cause instead?
"Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather, to skid in broadside thoroughly used-up, totally worn out, and loudly proclaiming: WOW WHAT A RIDE!!!!"