Well, I guess I see that in a way, but isn't this more a training issue for the staff? I mean if you want staff to be responsive to their customer's needing help, train them. I'm not seeing what the code word adds. I'm certainly not against it, let me be clear, I was just trying to understand.
I definitely agree with "the easier this is the better," no doubt.
I think you're really underestimating the level of unsafe someone can feel. Even if there's been no overt, spoken threat, someone can be very threatening, and someone can feel very threatened.
I think you also may be underestimating the number of people who would feel secure enough in no matter what situation, to be bold enough to go over to a bartender and say, 'I met someone on Tinder and he's creeping me out; I don't want to leave because I'm afraid he might follow me; I don't want to go outside in case he sees my car or the direction I go. I don't know what to do.' Honestly, if someone feels comfortable enough to do that, they'd probably be comfortable enough to do something else. A bartender or waitstaff is not likely to be most people's first choice in that kind of situation.
However, if someone is sitting there thinking their Tinder date might be an unhinged potential rapist or god knows what, and doesn't know what to do, and is wary of doing anything, lest the person make an aggressive move, or follow them if they leave, then thinking a bartender will know what to do to help, and that you can say 'oh, my friend comes here sometimes, I'm looking for Angela,' right in front of the person, and feel like someone is going to look out for you so you don't end up in a ditch...
I'd worry it'd get around as an idea but very few actual establishments would sign on or hear about it, and you'd have people saying it to an innocently clueless barback and then oy.