Trying to disarm someone with a weapon is justifiable reason for shooting them. There's only one thing they're going to do with that weapon after they get it. They're going to shoot you. Anybody crazy enough to do that is not planning to turn it in for a gun buyback
It's not a cliche to them. It is the normal reaction of mentally unstable jobless crazy people masquerading as political activists to a wide range of events, from being told the dollar menu price increased by $0.10 to hearing they are not allowed to buy malt liquor with their EBT card