This reminds me, women are more likely to be helped in a rape situation if they yell "Fire!" instead of "Rapist!" It's been psychologically proven, people are more willing to help if it affects them (like a fire) and are afraid for their own safety if they know a rapist is around the corner and are more likely to ignore it.
A whistle won't help in any way lol... What about a whistle would make people run to where she is?
Rape prevention and gun control are two different things, too. Instead of band-aiding the 'inevitable rape situation' with protection, how about teaching fellas not to rape ladies, hmm? That's a huge separate topic, but yeah.
Besides, most reported rape happens between people who know each other or at least are acquainted with each other. If you're going to a party with friends and acquaintances I don't think a gun is going to be the first thing you throw in your purse, either. Rape itself is a little bit of a touchy term with how it's applied, even if it's consensual at first, the girl (or guy, heck) could change their mind soon before or halfway through and if their partner doesn't comply, that's rape.
But, I'm assuming this guy is imagining the stereotypical girl alone at night gets forced into an alley gang-banger scenario.