uh....not sure i can say much more without the PC crowd hammering me to death. While none of us were there -- which is a big caveat -- from the description I read I'd hesitate to call what happened "assault". I'm picturing the assault on the Normandy defenses in 1944, in it's best usage. Or someone walking up to you and slamming a baseball bat into your face. Ouch. That's assault. But being kissed or having someone come on to you in a sexual/romantic manner -- even if you did not want it or reciprocate -- I think really stretches and abuses the language.
Here's one mental tool to help tease out the important distinction involved. Let's say the exact same thing happened as described in the story, except that the woman was sexually attracted to the man in question -- it would not be described as assault, just a man being aggressive and the woman liking it and being glad he did. It's pretty well known that a lot of woman like men to come on strong to them and be dominant -- of course the catch is they like this if they were attracted to them in the first place, but if they weren't, then it can have the opposite effect. Well, even if there were German soldiers stationed along the beaches of Normandy in 1944 who "kinda wanted" for the Allies to invade, it would regardless still be a military assault when they did.
Now add alcohol drinking, a bar, late night, partying, lots of rowdy behavior, touching, intentional flirting, geeks with poor social skills and body language cue reading, etc. and things become even more, shall we say, less clear cut.