Despite the YouTube caption, I don’t think the knife in question is a switchblade. Looks like your average pocket knife to me. (I half expected someone in the crowd to yell “That’s not a knife!” in an Australian accent.) While I don’t know the who, what or where, the why is clear enough . . .
The bandana wearing knife guy is making ye olde self-defense point: when seconds count the police are only minutes away. Lest we forget, at Marjory Stoneman Douglas High School, when seconds counted the police were already there and did nothing.
Anway, I think the parent could have handled the reaction a bit better, but point taken (so to speak). Yes?