That sailor tried to destroy the evidence afterwards.A sailor took a few photos of a submarine, for personal use, no intent to give or sell it; got removed from the Navy, went to prison ,probation and fines. Why is that so different than a person taking 10 classified files without telling anyone and just brush it off because he plays for your team?
There's over 20K sailors of rank E1 and E2 (typically 19-22 years old, as I understand it). I would think at least 10 a year or so take pictures of the wrong thing. I would guess most of them just hand over their camera or phone when they're asked to, as opposed to destroying evidence.
@Gameface might correct me here. Maybe it really is rare.