Something Stupid Happened Yesterday

Yesterday we had something stupid happen to us that I've read about but has never happened before.
We were FINALLY having our central air installed in our house and the air conditioner installer kept having to go in and out which naturally makes Aaron interested because of the door being open so he was staying close to the action area.
The guy was young and friendly and kept asking Aaron his name and trying to talk to him. At first I didn't say anything about the fact that it would be a one sided conversation, I was trying to feed Roo her lunch so I just stayed out of it, plus the air conditioner was on by this time so I figured he was probably close to being done.
Eventually, he said something to the effect of, he (Aaron) must not be a big talker huh? I figured at this point I would spill the beans, Aaron was, after all, rolling his eyes sideways and back in his head and making some weird noises while flying a truck .0000000001 millimeters from his eyes.
So I said to the guy, "Yeah he's not gonna answer you, he has autism and he's non-verbal."
Before I even got the sentence out of my mouth, he says, "Wow, he doesn't look like he has autism."
I have read about people who have others say this to them all the time about their kids and it has never happened to us.
It's a stupid thing to say...to anyone...about anything.
The people that I've read about will apparently say stuff like back like, "Well you don't look like you're stupid but here we are." Sounds like something I might say but I like to come up with my own stuff.
I could have said something like that and been a bitch about it, but the guy was nice, he clearly didn't know anything about autism, he was trying to be nice to Aaron, and our house has been hotter than crap for the last month and he wasn't quite done with the install yet. So I said, "It doesn't really have a look." That was just what came out of my mouth. I didn't know what else to say.
People say that so much apparently that on the autism support groups people often post pics of their kids with the caption, "This is what autism looks like in my house." It is always just a picture of a beautiful, smiling child.
To be honest it didn't make me mad that he said it, it was just a stupid thing to say. A lot of people say stupid things...about everything....every minute...of every day. There are soooooo many stupid people. Fortunately I don't have to really deal with many stupid people anymore since I quit my old job as a police dispatcher. Some, (I mean they are everywhere after all) but not many compared to before.
I wondered when I would encounter that statement, in what scenario, and what my response would be and now I know.
We shall see what happens next time. If the person is an ass the response may be different. Just sayin... ;)