
Defending developers
Apple has no option other than to defend the developers since they provide the development environment, development rules, and they provide the mechanisms to enable in-app purchase.
If Apple doesn't default to defending developers, it leaves itself at risk of litigation from the angry development community, some of which do have sufficient might to take on Apple.
And there's nothing an ambulance chasing no win no fee lawyer in Merkinland like to hear more than "Class Action Lawsuit"