here's how i see it.
I've seen a lot of 3 year olds who yell and scream and demand something when mom and dad are at the mall, be it a toy, icecream, or even stuff that I have no idea why a little kid would want (a power drill? a carry all caddy for a car? here i think it was the kid wanting attention etc)
Now, when a kid is screaming and reaching and all he is reaching for is ice cream, that is a disibline problem. Personally, it was unacceptable behavior when i was a tike, and i see it as unacceptable from anklebiters in my care.
However, screaming and reaching for a gun, especially a LEO's, your kid his putting his life in danger. This needs to be dealt with immediately and extremely, and yes, this may involve the kid crying a lot. A 3 year old reaching for a real gun should illcit the same reaction as a 3 year old about to push a fork into a wall outlet or about to take a drink from a bottle he pulled out from under the sink.