Involving yourself by commenting on very personal matters, especially in a smug or condescending manner, is almost guaranteed to end badly.
> He ended up grabbing me by the throat, while no-one around did a thing to stop him.
The bystander effect is real, but you should also take this opportunity for self-reflection, because in this case, you were the person behaving badly who instigated the situation.
> But I doubt I’ll learn anything from it
Yes, unfortunately it seems unlikely you will.
I’m afraid to say, that if you want a boundary, go home. Otherwise, accept that you’re in public, and people can and will speak to you.
Also, you’ve just justified being violent in response to someone making sounds with their mouth. I bet you’re a calm person to be around, when everyone does what you want.
> In what world do you live?
In what bubble do you live? Go out into the world and behave like the GP. Your apparent mental model of society will collapse quickly.
> Go out into the world and behave like the GP. Your apparent mental model of society will collapse quickly.
The problem you’ve got is that I will win. If you permit escalating mouth words to physical violence, I’ll have stabbed you in the face for your mouth words before you’ve gotten very far. Subduing your propensity for physical escalation is in your favour.
Of course you would. What an infantile response divorced from reality.