Re: Seeing Another Child Who You Think Is On The Spectrum...What to do?
Well, how close are you to this family? If it was the child of a relative or close friend, I'd probably just come out and say it, unless my experience with this person led me to think it was a bad idea. If I thought a stranger's child was ill, I wouldn't say anything unless I thought the child was in immediate danger of serious harm. "Hey, your baby's lips are blue, do you want me to call 911?"
Sounds like this is an acquaintance, somewhere in between.
One thing you could do is talk to the coach about your son, start educating him about autism, allegedly to better work with your child. Then you could see how the conversation goes from there.