This particular "remedy" didn't make much sense or have any technical logic that I understood, but I tried it anyway.
I tried the recommended closing of the AppStore in the task bar, then double rebooting. I actually attempted this twice (twice closing the AppStore and rebooting twice per time). It didn't fix anything. The AppStore update window is a blank screen that never loads.
I'm 99.99% certain that this is an issue Apple needs to correct on their end. You can reboot your iPad a thousand times, reinstall its software, take it to the Genious Bar in Apple Stores around the world, fly it to the moon and back and chant with Tibetan munks. There is nothing anyone can do to correct the issue on their end. Apple, and Apple alone, holds the key to this issue. It's a server-end thing. It may also be fixed region by region, so if someone *does* report a "fix" that they believe truly worked for them, they're mostly likely just in a region that the issue was fixed in around the time they attempted to "fix" their iPad AppStore issue. Either that, or they're trolling for suckers to try rediculous "remedies" and report back about it... kind of like what I just did.