“Kramer” of Seinfield fame was dragged off stage in the middle of his comedy routine because of using “racist language.” He failed to read his audience.
That whole incident reminded me of another audience heckler situation, in which the late-great George Carlin informed his audience that the guy was just making a big fuss because he wanted a particular object jammed into his mouth to block the noise. He then told the audience member, in detail, how he would kill and maim his family if he didn't quiet down or leave the theater.
Not that I'm making excuses for what's-his-Kramer; but Carlin was able to get away with saying some really nasty things to an audience member, and still get laughs while doing it. Whereas, Michael Richards practically got drummed out of show buisness. Because, like Ramm said, he couldn't read his audience, and doesn't have the same knack Carlin did for dealing with "objectionable language" in a way that's funny.
Point being: Maybe it's better to expect "non-knife" people to be prejudiced, and have prejudicial opinions about people who carry and use knives.
Maybe even treat them like they're "racist" in their own way. With a little bit of outrage, but mostly just letting them know that they're being ridiculous and even offensive by inferring that you're prone to violence simply because you own and carry a pocketknife.
It's a deep-set prejudice, and like almost all prejudice it's completely irrational, self-reinforcing view on a particular group of people, in this case knife users. There's no point in just being nasty to people who don't understand why you carry a knife. That just reinforces the prejudice.
The only way to deal with it is to offer reasonable explanations, and go out of your way to be pleasant, but make it clear you have the same right to be free of prejudice and intolerance that any other group of people does.