I'm of the opinion he should never learn to use straps. Get him clipped in and make him learn a nice round stroke.

If that is NOT going to happen then get him to try some that he feels comfortable with HIS shoes. He's going to be really fussy about his shoes so make sure he's cool with how they feel and how it will mark up his shoes. LBS is where you need to head. A good one though, no BS shops.