Greg Cochrane mentions that here, http://westhunt.wordpress.com/2012/08/22/paternal-age/ , in the context of the influence of paternal age on mutation rates, and excessive numbers of mutations having negative influences on fitness and health.

Correlation != causation.

It could be that men with some medical condition are both likely to father an autistic child and to postpone child-rearing for health reasons. Heck, the autism itself in a very mild form might be such condition - a mildly autistic man could be likely to pass more severe autism to his children, and have problems finding a mate.