If she didn't notice, he wasn't ogling, or gawping. I check out men all the time. I'm not blind or dead and I'm attracted to men. They never notice. Why? Because there's a world of difference between quietly and surreptitiously enjoying the view and then going about my damn day without intruding into theirs and gawping the classic wolf cartoon in days of yore and making a fucking spectacle of yourself. Just saying.
I read that article you referenced too and, I don't know, you have a point but I think she has too. Personally, I would have been alarmed. They were drunk, which lowers inhibitions, there were young and inflamed from a sporting event as I recall so there are pack dynamics to consider, there was no one else around, and had they followed me home, they would have found me going through isolated areas at night. As you say though, mileage varies.
Would I have been afraid? Maybe. I'm armed so two are fewer and I can defend myself reasonably, though there's never any guarantee. More than that changes the dynamics somewhat. I would have gone to evasion tactics. I might have called an Uber to meet me at my stop so I don't have to walk through those problem areas.
The big thing and take away is the aggravation of it all. You made mention of her dress. I felt that was mostly hyperbole but I see her point there as well. What a let down! She's in the middle of a Queen of the World moment and it gets ruined. Imagine Leo climbing down off that railing and stepping in dog shit. And then having horse nuggets thrown at him from drunken rich passengers having a go because they're bored and he, being a C deck passenger is expendable. Same thing.
The bit about the dress was that they made her question herself. She wore that dress in a professional capacity (whatever that business thing was she just knocked out of the park, I don't remember) and now she's wondering if the reason she was received so well was because they too, desired her in a sexual capacity. So now, if she wears that dress again at work, will she be harassed there too? So now she's also questioning the motives of the men she works with. That's going to ben the back of her head for a while. How could it not be?