clear sexual advances like these without invitation are a clear case of sexual harassment.
So you want to ban any kind of sexual advances? I mean, do you want that people first ask before they ask about starting a relationship? I mean, that person didn't touch her, or even intimidated her or something.
The only real problem here was that it was a superior asking a subordinate. THAT is bad behavior, as there is always a direct power relation.
The second problem obviously was that it wasn't his first encounter like that, but one does have to ask whether his other encounters were with his subordinates as well, or whether it was simply with other coworkers (which is okay).