What the GP is arguing is that web apps pinned to the home screen are no different from those same web apps viewed in a browser and therefore, there doesn't seem like there should be any security issue involved in it.

Someone (who I think works on Cydia - the Jailbreak App Store) commented about this further down:

Of course, this means that there is no real good reason why Apple has disabled Nitro for full-screen web applications (that I at least yet understand), and so I'd expect that this was frankly just a silly oversight