I thought it was kind of odd. Why do they prefer someone without 1.5 or 2.0 experience. I did some Google and found a basic rundown of the differences. The job post does not list WCF experience or LINQ or Entity Framework or MVC.
3.Other basic concepts
.Net 3.5- Enhanced Feature of .Net 3.0
For more details you could always look through these but that is not really the point of my article.
At first I thought it was odd but then it clicked. This kind of reminds me of the article written by Ryan O'Connell about all the things you would have different opinions on.
So I am guessing that rather than a technology requirement in as much as its a personality requirement. If you started with .NET 4.0 you don't know any of the sloppy hacks we had to do regarding stuff as simple as reading the config file. Remember the including of a separate DLLto read the web.config in 2.0 as opposed to 1.1 having it native in the DLL. I guess if you remember that you don't qualify for this job.
I look forward to hearing other your comments. I know I would prefer someone who has been through the trenches than one who just arrived as a new private but that is just my opinion how about you.
If you have more insight then please email me at email@example.com or firstname.lastname@example.org