With all due respect, I think our entire culture needs to try harder to be clear and concise when communicating. I can understand protecting herself from guys that won't take no for an answer, but that type of disrespectful male behavior should've been corrected by their parents when guys like that were kids in the first place (which is another, equally complicated matter to find a definitive answer to).
I guess with how human socialization currently works, her answer is probably necessary in the long run, but I also think it's better to play it on a case by case basis, because there are also some guys who ONLY rake no for answer, which nullifies the original strategy. I'd also say that not enough women are willing to stand up for themselves and give a clear and definitive NO at this moment, which also hurts their ability to have an equal standing when confronted by others with a toxic and controlling nature. Saying no and being clear and dominant in the presentation of it is very important in situations with dangerous people like that.