Has economist been too far from their turf?

If you are a subscriber of Wall Street Journal, you can read the following article discussing about an economist try to propose a prescription for autism. It is not free, though, and I will post discussion later about why WSJ is not freely available while the other main presses do.
Is an Economist Qualified To Solve Puzzle of Autism? - WSJ.com
And here is the excerpts:

In the spring of 2005, Cornell University economist Michael Waldman noticed a strange correlation in Washington, Oregon and California. The more it rained or snowed, the more likely children were to be diagnosed with autism.

To most people, the observation would have been little more than a riddle. But it soon led Prof. Waldman to conclude that something children do more during rain or snow -- perhaps watching television -- must influence autism. Last October, Cornell announced the resulting paper in a news release headlined, "Early childhood TV viewing may trigger autism, data analysis suggests."

Although the report is not free, the paper is available here

My thought about this is, I feel some economists are really way too far. Maybe I am too old-fashion in some sense, but I really don't appreciate some researches that crossed boarder too much. In this autism case, I do think its a worthwhile try, but it should be accompanied with some experts from the other area. Economics is about human choice and human interaction. Is autism the result of choice and interaction? I don't think so. The evidence it relies on, as this report disclosed, is the instrumental variables method, a tool that has been widely used by economist. Basically it's a method that try to create natural experiment ex post. It has been widely used as well as widely criticized. I am not intend to judge it here, but I do believe if economist want to do something outside the turf and convince the others, we may need something more than IV methods. Maybe cooperate with the other experts could be a good start. Also, here is Steven Levitt's comment on this paper.