Should women have to be more direct? No. But is it safer? Yes, absolutely.

I'm afraid I don't buy for a second that women are put in more danger by not saying anything explicit. This runs counter to all common sense and all of my personal experience. Society already pressures women to never assert themselves, always remain passive, and you're further encouraging that!

You know why people avoid looking at you awkwardly on the bus, or point and stare in the bar? Because you don't say no. Everyone feels the awkwardness, but there's nothing they can do to shame or stop the guy because no one in this world is a mind reader. The moment you say you're not interested or make your position clear, society is on your side. Other people will help you out, strangers will try to shame the idiot, and it's not something you have to worry about any more. I can't count the times I've sat awkwardly next to some girl who clearly is being bothered by someone, but won't say anything, so we all have to endure it rather than getting up and kicking the asshole out.

You may ask, if it's so clear that she's being bothered, why don't I do anything anyways? Because if I did it would be just as sexist as the guy who is bothering a woman. I'd be saying that my interpretation of a situation as a man uninvolved is more valid than yours as a active participant, and that I've decided you needed my help without asking. The assumption is that if you were actually uncomfortable, you'd say no, however wrong that assumption may be.

Every single time I've seen a woman clearly say no, it's ended well. Either they aren't bothered further, or other people help them get rid of an asshole that won't stop. Many times when a woman doesn't say anything it escalates, people are afraid to jump in, there's tons of social coercion, and often they end up doing something they don't want to.

So if you want to talk about safety, I will flat out call you a liar for saying women are safer not saying anything until you have any data to back you up.