Clipless pedals are not always the answer, commuters (like your son) wont ever need most of the added benifits of clipless systems, and the disadvantages will be highly magnified.

My favorite combination for comfort and durability is the All City double straps with the soma 4 gate cages. While the redundancy of the double straps and 4 gates may not be necessary for his style of riding, it will be much more comfortable than a single strap 1 gate system.