In that environment, how many under 16 year olds would be allowed out drinking and partying. She fitted right in so he didn't question it.
Loads, actually. I remember being at school and 15 year olds were going out partying. There was a club well known for letting anyone in. It shouldn't happen but it does often. It happens enough to know that someone who claims they are 16 could be lying about their age. Not all parents check up on their children when they claim they are staying over a friends etc.
You can't condemn 19 year old men for wanting to have sex - that's a normal human drive.
I can condemn them for picking up someone they thought was barely legal and taking her home for sex all I like. I don't give a shit if having a sex drive is normal, I do care when people are picking up what they think is a girl barely legal for a ONS. I know, I'm stupid to have higher expectations of 19 year old men. Horn dogs that they are can't control their drive enough to think shit through.
Even if the thought had crossed his mind that she might have been lying about her age, I doubt for one second that he could have believed her to be under 13.
Oh so it's ok as long as he believed she might have been only year or two younger than she claimed?
The 12 year old should never have been there and another adult has some responsibility for how she was allowed to be.
Indeed she shouldn't have been there. The one responsible for sleeping with her in entirely down to the man who slept with her.