Ah, the jorts insult thing. There are many theories, but no one seems to know where it really came from. It seems to be kind of specific to sports fans in the SEC (because really, no one from anywhere else in the country is ever going to be wearing shorts of any kind to a college football game -- too cold at night.) Funny article on the topic:
http://www.cbssports.com/spin/story/10296963
This isn't the first regional brouhaha over what to wear to a college football game. In my day (early 80's), standard attire for an SEC football game if you were male was a pr. of khaki trousers, and either a button-down dress shirt or a polo-shirt (preferably Polo). If the weather was cooler, the button-down would be worn with a sport coat and a tie. Girls wore suits, or dress trousers/skirts with a silk blouse and pearls. Yes, we dressed up to go to football games -- it was a tradition. Students from up north were always freaked out by it. (BTW, You'll still see a fair number of women in dresses and pearls if you go to a tailgate party at Ole Miss.)
I don't live in the South any more, so this whole issue is just a curiousity to me. However, I'll agree that jean shorts can be a bit of an oxymoron if you think about it. If the point is to keep cool, wearing heavy denim in a tightly constructed style kind of defeats the purpose. The guy in that photo above is also wearing really pale denim, which is badly out of style at the moment, long or short.
FTR, DH does own a pr which are actually olive green canvas -- he wears them for yardwork.