I don't quite get it though. I always had issues to distinguish what Americans call Sexual Harassment and what is just flirting (and yes, I lived and worked in 5 different countries and the only country where this is a such a big problem is in the USA).

The putting her leg on his lap thing sounds, to me, like very awkward and yes, aggressive advances.. but it's not like he grabbed her ass or something like that. He's also not in a position of power, unless I'm misunderstanding something... so I'm having a bit of problems understanding what the issue is here.

As long as she makes clear that she's not into it and he drops the issue, why is this such a big deal?

From the above comment it just looks like he's very awkward at flirting and has no finesse.. but that's it.