I just said much the same thing.
I recall a story where a mentally retarded teenager was shot down after being badly burned in a vehicle accident. [...] He refused to lay down on hot asphalt with first degree burns all over his body.
That doesn't sound retarded at all to me.
What does sound retarded is: vehicle-accident survivor* —> shoot-him!
* Esp considering a vehicle accident could easily be a cause for traumatic brain injury, in which case that "acting erratically" is actually a symptom.
You are correct. Brain injury is very often leads to violent and irrational behavior. This behavior of a stunned, injured motorist can lead to a field execution by a cowardly cop who has no desire to sort things out. Much easier to just start shooting. Safer for the cop who just wants to preserve his own skin and his gubment cheese fueled lifestyle.