This one hits close to home and is a debate we've been having in the DE Autism community forever (or at least since I've been around).
Sadly, I have to concur with a large part of the author's hypothesis. Most of the reason there is an explosion in the apparent growth of people with autism is awareness and education. I'm not as cynical to say that this is largely predicated on people trying to garner more funding for research or whatever. Rather, there are more and more parents who see their kids slipping away from them and are desperate to get them back (count me among them).
Personally, I think autism is a confluence of several things happening at once more like a syndrome than a disease. Some researchers have shown strong links between mercury and autism. One study showed that mercury has a deleterious effect on motor neurons but that effect becomes absolutely devastating when testosterone is added to the mix. (That would explain why a vast majority of autistic people are male). Others contend it has to do with the ratio of white matter to grey matter in the brain. That is connective vs. cognative tissue. The latest study I've read is the immune system plays a big part in autism somehow. Just how is unclear as of yet. Other theories have to do with teflon, cassein and/or gluten product, leaky gut syndrome or other environmental factors.
California has done the world a huge favor by collecting massive amounts of data with respect to incident rates and demographics. They have shown that the removal of Thimerisol has had little effect on incident rates over time. The upside is that Autism is now become the cause celebre for the Hollywood set. I bash them daily but their advocacy for any disease is very very welcome. Those that affect me and my family doubly so.
In short, casting a light on something that affects so many people increases the likelihood that there will be an effective treatment, cure or even preventative measure we can take. What advocates often miss is the practical case for treatment. The social cost is very high for people who are low functioning autistic. They need to be cared for their entire life. They cannot live on their own, feed themselves, dress themselves etc. Put those numbers to the American public and you'd probably see much more support for research and early intervention.