So you are telling me it is okay to murder someone for that? If someone killed a man in a dinner for doing that you would be fine with the police not arresting anyone?
If she is being harassed there are laws to protect her, call the cops on the asshole. This is not the middle of nowhere and letting people solve their personal problems with violence is exactly how we end up with drive byes in the streets.
Also I wonder if anyone would be cheering if the genders had been reversed? I have worked service jobs all of my life and I know some people will find this hard to believe given my picture but I have been harassed to the point of having woman and in one case a gay man slap my butt and I never once thought about killing them or threatening their lives. Is that really what i should have done and if I had done that to a woman would you be okay with that? The problem isn't so much what they wrote as the setting they put it in. Normally when the hero does something like that it is in some lawless area like a frontier town where they are the only protection for a whole group of people. Here it was not the case to it just came of as the actions of someone with massive rage issues. Not only that but I am not convinced that this would have fixed the problem. If the man really is an abuser to the point where this action is required I have seen what happens next in these type of situations in real life and she didn't solve the problem, all she did was embarrass him and make him mad and that just increases the odds that he will either get violent with her friend(Since Carter can't be there 24/7 to protect her)or he decides to get revenge by going to the police and showing them the marks she would have left on his skin and saying that they were both in on it and then her friend not only gets fired but may end up in jail.
In other words either the actions were not warranted or if they were they would have only made the situation worse. Either outcome does not make Carter look good and since it didn't seem to set up any sort of character or plot arc I am just going to put it down to bad writing. The character was written well in the rest of the show, but this one scene just really didn't work.