I think these 'push back the release' reports are mostly just sensational reporting. Apple is constantly adjusting plans for things that aren't ready to be made public yet.

Part of the reason they are so secretive is because anything that hasn't been announced yet is subject to change and they don't want to promise something until they are certain they can deliver it.

So unless they actually announced a release date, they haven't 'pushed anything back'. This is just an internal review being leaked in a sensationalist way.