if he's afraid of looking stupid/incapable, or if he's sure he can't meet his own expectations of himself, would it work to rent/borrow a scooter for your mom--but not have quite enough time to help her get used to it and figure out how it works..and let him have time alone with the thing?

It's not exactly Vanity that makes women dye their hair startlingly dark after their eyebrows and eyelashes have faded white and the rest of them looks ancient.
It's not exactly Fear that keeps men from buying what might be their last pair of boots.

If he's worried about not being A Man, maybe he could be remasculated?