[dqh]

In the absence of power imbalances (doctor/patient, teacher/student, police/suspect etc), I think in general it's acceptable to make the first part of a first move if you have reason to believe that it is welcome - it becomes crystal clear whether it is or not very quickly. But obviously, the instant that rejection occurs, anything other than a sincere apology for misunderstanding the signals is unacceptable. It's a bit embarrassing, but you get over it :)

As for this (theoretical/alleged/etc etc) story - it doesn't sound like the guy even had reason to believe that his first move was welcome. She had flirted with a couple of other guys, and sat on a few laps due to the lack of seating in the hotel room. As someone with a lot of female friends and who has been at a lot of drunken parties, I can say that this sort of thing is common, lots of fun, but NOT an invitation for any random guy within the group to make a move. There's a big difference between general flirty fun across a group and a girl specifically and exclusively flirting with a single guy. It can take a while and a few mistakes to learn to tell the difference. Especially if you have spent more time on your computer than with friends as a child/teen and you haven't yet realised that the way these things happen on TV aren't how they happen in real life (yes, I am speaking from experience ;D ).

Pro tip for my fellow geek guys: Don't hit on the geek girl. Focus on being awesome. If there's a chance, she'll hit on you. If not, you still get to be awesome.