Doubly secure Windows Store

I was looking around the Windows 8 App Store just to consider whether I was going to upgrade to 8.1, and then I came across this very strange "security" category

win_store_security.png

See that all other categories seem to highlight 2 (and sometimes even 5) different programs? Well, what it looks like is that security is "locked" and I can't add any security apps to my computer. Isn't this strange? Yes, it's Windows...