Lots of the touring bikes would work - a shop should be able to work on the wheels to make sure they're properly tightened, and sturdy. That would owrk well, too, given your goal. He may still break spokes - and may eventually need hand built wheels. Most bikes would actually work - I would worry more about the wheels than anything (though there are those who say that even the low spoke wheels work).

Kudos to him for wanting to ride - and what fun!!

CA