I think that you shouldn't be a jerk. Very few newbies understand the difference between a experieneced rider and someone that's just starting. It takes a couple of years for most people to grow in enough capilaries in their legs to get rid of the muscle wastes from hard riding. Occassionally someone is a natural (like my exwife and all three of her daughters) but it isn't very common.

Take your LeMond and RIDE with him. That alone will be enough of a challenge since at the end of a 30 mile ride while you're as fresh as a daisy he'll be exhausted.

Dropping him or making him look stupid will only discourage him. You want to encourage the guy.