You'd never know just by his job. Military barber used to strictly be an enlisted position, before they instituted a program to allow independent barbers to qualify for preferred status near bases. And still today, enlisted barbers are aboard Naval vessels and at secure stations all over the place.
But Mott is a civilian, and is listed so at Memory Alpha. He's probably a crewperson's spouse although that's never been shown. And he probably barbers, and gets crewpeople to let him barber, because he's alright at it, and because the barbershop environment provides a social interaction you just can't get from the 24th century self-grooming devices they almost certainly have in their quarters. Same as having a bartender, I guess.
Good call on Vash, btw.
