After reading this entire thread and double-checking the posts, I can say that you are not getting this. Before you go off in the direction of reading comprehension or something of that nature, I am above average intelligence and possess a significantly higher level of reading comprehension than I see you do, judging solely from your choppy grammar and punctuation.
You can in no way whatsoever, under any circumstances, speak assuredly about what she "should have" done. Yes, you are correct in that if no one tells him what he does is wrong he will almost certainly never realize it on his own and self-correct. However, when you are getting tattooed by someone you are in a very vulnerable position. This person is doing something that is, for all intents and purposes, permanent and possibly holds great significance for you. That puts them in a position of extreme power over you, especially because you went to them and theoretically chose them over any number of other people to make this for you.
Now, add to that the fact that this person has made an unwelcome and lewd comment with the underlying tone -whether intentional or no- that they can make whatever comment they want to you and there's not much you can do about it, and that puts you at an extreme psychological disadvantage for speaking up for yourself.
On top of that, when she comes to look for people who have had similar experiences and vent about how she was mistreated, she has narrow-minded fools coming out of the anonymity of the internet to tell her that, wait a minute, this is mainly her fault for not going extremely far out of her comfort zone and correcting the behavior of someone who has the significant psychological upper-hand in the situation. You cannot equate her situation to one of where your artist showed you something and you didn't speak up about not liking a portion of it. She was in the predicament of actually being tattooed and the person who was tattooing her sexually harassed her. Whether you like it or not, sex is a very private thing to most people and not discussed openly or casually with someone who is ostensibly a stranger. That can be a very violating and even traumatic experience, ESPECIALLY when this person is doing something to you that has a deep significance and will be with you permanently.
And before you start talking about what you would've done and how you would've handled it and how you would've told the guy to "back off, bub", please take a step back and look at yourself. I can think of multiple times on this board - including one interaction with myself - where you've made a bold, poorly-thought-out statement and back-pedaled immediately when someone called you out on it.
It's not always so easy to stand your ground when you're put on the spot. Please consider the circumstances before getting mouthy on the internet.