My comment about the spin class was just about his motivation. You can't do a multi day ride if you're not fit and from the original post, I'm inferring he's not. And if he hasn't been back, is he motivated?

It sounds like he doesn't have a bike yet, so he's not riding outside. If you're going from a base of nothing to riding several hundred miles in a week, in less than 4 months, he needs to get training.

Be supportive and encouraging all you want, but he has to ride the miles and they are not flat.

V.