What is unclear if that they don't know if they keep trying whether she will eventually speak to them, they obviously think what they have got to say is extremely important or they think their persistence will pay off, they need to be put straight.
I'm not saying they are right, they aren't, I'm saying ignoring a problem is not making it go away, OP needs to make her WISHES KNOWN then refuse to engage.
If you just refuse to engage, chances are the person is going to keep trying, no that is not your fault.
So a man is bothering your daughter in a bar.
Comparing someone turning up at your door who is apparently a relative who wants to talk to you about something vs drunk predator 'bothering' you in a bar is very goady and not at all comparable, plus in a bar you have someone who you can escalate that to (bar manager), and police if they are acting inappropriately.
At no time have I said OP is 'at fault' for this interaction, but ignoring something won't automatically make it go away.