Well, a lack of understanding can actually make people more comfortable; he may not have realized his parents were dead for example due to a lack of comprehension of the events. He seemed to be quite unaware of the environment in many scenes; crossing the road and whatnot. Whilst I lack the ability to recognize the danger in certain things, I know that car equates to pain and/or death if one hits you, so I know not to cross in front of them.
It's known that the lower the IQ the more passive the individual is; things that set him off might not be what would set those with a normal IQ off.