There are no two ways about it, pulling out a knife to clean for no reason, regardless of how big or small it is, can very easily be viewed as brandishing (which is illegal in most states) and potentially threatening. While the reaction of the lady to the knife was obviously a little extreme, a knife is a weapon alongside being a tool. Pulling a knife out for no reason is not socially acceptable behavior, and treating it as socially unacceptable behavior is not something that should be shamed. The name calling and multiple attempts to try to politically charge this topic should be shamed, and I'm a bit surprised a mod hasn't stepped in and shut this down already.
The lady's reaction was over the top, but knives like many other things we all have should not just be whipped out for no reason. Right to carry is not right to brandish. This could have been ended with a simple apology for obviously disconcerting behavior, but it was instead taken to an internet forum... to try and get props on disconcerting behavior? Don't pull out a knife for no reason, that kind of stuff makes us all look bad. Clean your knife at home, man.