My point was that I don't believe this is Apple's primary motivation. If Apple wanted to allow arbitrary code execution, they could have an entirely separate c

My point was that I don't believe this is Apple's primary motivation. If Apple wanted to allow arbitrary code execution, they could have an entirely separate category of app for it that includes warning labels, and requires the developer to justify to Apple why their app requires arbitrary code execution in order to function. If someone submitted a flashlight app that requested this capability they could just deny it. E.g. they could say that the only valid justification for allowing arbitrary code to run is for developer applications that are meant to be running user written code. Apps in this category could be forced to pay extra to apple in order for Apple to pay for special, ongoing scrutiny for security reasons. They might even do things like require that the app publisher be well recognized and have some sort of provable, good track record of not releasing malware. Arbitrary execution is not incompatible with review, it makes it harder.