I believe there is a correlation between IQ and impulse control
That doesn't sound right. Impulse control is industriousness, an aspect of personality. IQ is intelligence, which isn't a personality trait. There are intelligent impulsive people and slow diligent people.
When you insult someone you use whatever you think will hurt them. Personal beliefs don't enter into it. I bet most racial slurs said with intention to insult aren't even made by racist people, just momentarily angry people.
Maybe it's not fear. Teachers may have turned them against their parents during the brainwash phase. A year or two of hints to find out which kids are receptive to the ideology of resentment before you bombard those few with whatever they need to hear to allow you to "save" them.
What's gonna be the argument, that after wrestling the gun the attacker was unarmed and therefore the shooting was disproportionate? Did the attacker lift his hands in surrender and was shot after two seconds of the owner thinking it over? Even in that worst case scenario, I'm not sure if it's appropriate to punish the owner.
Lawsuit wouldn't work if it's legal.