And actually, merely adding features doesn't seem to be forbidden as long as the features you add are not "inconsistent with the intended and advertised purpose of the Application as submitted to the App Store"
So let's say you release a file manager and later, surprise! It's also a SNES emulator! Well, then yes, I can see that against the TOS. But if you're just making improvements to your app, I don't see a problem.
It was just a hypothetical though. AppHub has plenty of legit use cases under Apple rules, and it's probably not all that dangerous even if you "mis-use" it slightly. AppHub would have to explicitly encourage people to break the rule to run afoul, or Apple would have to organically notice a bunch of apps doing a bunch of outlandish feature flipping.
However I think advertising it as a mechanism to get around the App Store review process is a quick way to get noticed by Apple, and not in a good way.
* If the AppHub founders think this is a real danger, then you'd expect bold and strenuous documentation.
* But, I wonder if the AppHub authors believe that people should ignore this rule, because practically speaking it's hard to get caught. They wouldn't say so, of course, because encouraging people to break Apple ToS is illegal.