Generally, I agree that the two being worn simultaneously is redundant, but something to keep in mind is that a man of his age has seen a lot of mileage, and with that comes a lot of wear and tear on the vehicle. It may be unlikely, but there could be age or illness related reasons preventing him from tightening anything around his waist (colon-cancer, for instance). Or, maybe he just finds the braces more comfortable and likes the convenience of the utility attachments which can be added onto the belt. You know the saying....form follows function.

Cheers,
-Jake