Most Helpful Guy
Guys like sex, and many/most guys would have sex with an attractive, willing girl if they had the opportunity to do so. HOWEVER...
Most guys would consider any girl who had casual sex so quickly to NOT be "girlfriend material." He might use her for sex - even be friends with benefits with her, but most guys will never consider dating her. Why? Because he will assume (and always worry) that if she had sex with HIM so fast and easily, then she'd have sex with other guys the same way - relationship or not. That means NO RELATIONSHIP.
There's nothing wrong with wanting casual sex, and getting it, but don't do it with guys you think you might EVER want a relationship with, because you will ensure you'll never get it.
Most Helpful Girl
He probably doesn't see her as much of anything in particular, other than someone likely to have sex with again. He's more or less stranger!