It is possible that if he was older, that look on his face was more of a "who is that, do I know him?" look. My dad and my 2yo nephew have that look sometimes. I doubt anyone would be disdainful to someone waving hello. Maybe he realized 996's say hello now and he will start saying hi too.
I don't always get the wave from 996 or 997's when I am in my older cars, and never get them from boxters. We'll see about the Caymans.
