Earlier quoted context omitted.
Yes. GPL apps can't go into the app store, because it's terms of use forbid activities that can't be forbidden according to GPL.
I don't quite understand this. The GPL gives the end user the rights to the source, to modify the source and to redistribute the software (modified or otherwise), as long as they make the source available. It doesn't say it has to be available through the exact same mechanism that you received the software in the first place, nor does it say that you have to release your changed software through the same mechanism. I…
On iOS, Apple enforced code signing on all apps, so a user cannot download an app’s source, modify it, and use it on their device. Code signing prevents that, therefore would be a violation of GPL.