From a reader:

Should we be open to the possibility that these government agencies and businesses have blocked all sites with “jihad” in the title, in an attempt to make sure their employees are not looking at terrorist websites, and JihadWatch got caught up in the mix? I don’t know how this kind of blocking software works, but unless it is always done on a site-by-site basis, that would seem a potential explanation.

UPDATE:

Another e-mail:

Companies that run blocking software usually subscribe to vendors who sort websites into more easily understood categories. For example, our vendor, SurfControl, categorizes Jihadwatch.org as “Blogs and Forums”.