Get him a Lemond Buenos Aires. He'll be hooked forever.
Seriouly, I personally wouldn't get him a Trek 1000. It's not a geezer friendly bike.
If there is any chance he'll get into roadbiking, I'd get him a Lemond Reno. Great bike for the bucks. Several members of the old goat's forum ride them and love them. They handle a whole lot better than a Trek 1000, IMHO.