Of course it's just possible that the passenger being made fun of here for apparently not having put his lifejacket on correctly could have shoved the bladders out of the way so that he could swim - otherwise he'd be continually turned onto his back.
Meanwhile look at the woman - who is possibly a flight attendant - working on a leg injury. She's made the sensible decision not to inflate her lifejacket at all - because at that moment it would have got in the way. People aren't necessarily complete idiots - even when they're under stress.