I think these yawning posts call into question the prevailing idea that people on the spectrum are less likely to yawn contagiously, and so the underlying mechanism doesn't function.
What I have noticed in the responses is that people on this site seem to either not respond to yawns or they have a hyperactive response, like myself. The word yawn, the idea of yawning, images of yawning, animals yawning, can all send me into excessive fits of yawning.
What this seems to suggest to me is that it is not a matter of the underlying system not working, but instead, not working properly.
I do admit that I may be victim of the selection bias, those who do not experience an extreme response either direction simply may not be interested in these post. I do however believe it is still worth contemplation...