Juud, Lemain, flyblue,
with all due respect to your professionality and experience, and though I would not normally venture to post in this forum, let me kindly suggest that the discussion is touching a very sensitive area at this point, but still one where people from different cultural backgrounds will have rather different points of view.
Universal declaration notwhithstanding, the breaching of private sphere, and with a sexual intent at that, will be considered a very serious matter in some places and times like e.g. in the workplace by a modern-day American, and rather less serious in others. That's not voicing an opinion or stance either way, it is just stating a fact. An extreme example of a different stance might be if the same had happened during Carnival in Venice in, say, 1620. You get my point I'm sure. So yes, the person who did it will and should be prosecuted according to the laws and rules in force on the aircraft. That still leaves it perfectly acceptable that some people would not consider her behaviour criminal, but just silly, though. And that does not mean those people are in any way "wrong" or bad; they simply apply a different moral yardstick; and of course, in many jurisdictions, if the victim does not feel victimised, and does not sue, the perpetrator may not be prosecuted.
Please forgive me for this this somewhat theoretical intrusion in the discussion.