"The GPL prohibits use on the iPhone" is not an equivalent statement to "The Apple ToS is incompatible with the GPL". Nominally, consumers own their devices, and in most regions it is legal to circumvent Apple's digital manacles to install software you choose on your hardware. If you want to do this to install GPL'd software, you are fully within your rights to do so.

I think it's rather backwards to say "the GPL forbids distribution under the App Store ToS", because the GPL has no concept of Apple's app store. The GPL predates the Apple App Store ToS by decades. Apple was actually forced to consider this policy when the VLC event happened, and chose to maintain it.