I'd like to share a story with you, if I may, that might shed some light on the subject.
When I was in elementary school, I didn't understand the social thing. I didn't get personal space, or waiting for a pause in the conversation to talk, and my personal hygiene was lacking.
This did not go over very well with the other kids.
As punishment for my out of bounds social behavior, the kids at my school found a fitting punishment for me: they threw rocks. They were never very big rocks- mostly the pea gravel from the playground.
In contrast, any kind of guidance from parents is sweet and kind by comparison.
Think about a tsunami
Most of them are caused by an earthquake in the ocean. This earthquake doesn't have to be very big; it can be fairly small. In the middle of the ocean, a tsunami isn't very big- only about a foot higher than normal sea levels. As the earthquake causes a shockwave that travels closer to shore, the wave caused by the earthquake becomes more visible as it increases in amplitude.
There are stories of Japanese fishing vessels going out to sea on a calm day and returning at night to find their villages destroyed by tsunamis they didn't even see.
This is like the social thing. NNTs are like Japanese fishermen out at sea; we can't see the tsunamis until we get close to shore again. Everyone else are like villagers; they can see the tsunami coming. Parents, teachers, psychologists, etc. are like scientists: they have the equipment to see a tsunami coming- they might even be able to teach the fishermen to use those instruments.
Now, if you don't know what a tsunami is- or what causes them- you might attribute it to God, or demons, or Cthulhu. That's where parents come in: they can tell you that it is not God or Cthulhu, but an earthquake/weird behavior that causes tsunamis/rock throwing.
Today scientists have equipment that can help detect earthquakes that cause tsunamis; they detect changes that aren't visible to the naked eye. Even with this equipment, if you were to be in the ocean above an earthquake, you might not see anything other than a small wave. But you are a scientist! You know an earthquake has occurred- your instruments say so.
Children can be incredibly cruel and mean. If you love your kid and tell them so, and just keep trying to teach them the social thing.
I almost never get that my behavior is a problem until it becomes tsunami-sized. I still sometimes don't see others' facial or body expressions unless they are tsunami-sized. I forget to use my science equipment to look for the early warning signs of other peoples happiness, sadness and anger.
As a parent, your job is to give your child the tools they need to successfully navigate the world around them. If you are doing your best to prepare your child by teaching them facial expressions, you can bet that your techniques are more kind than the techniques used by your child's peers.