Turns out it is the former as Apple has since officially acknowledged that the kernel on iOS 10 was left unencrypted on purpose. Apple had initially declined to comment, but since the issue got so much Apple, they decided to release a statement to MIT’s Technology Review in which they said, “By unencrypting it we’re able to optimize the operating system’s performance without compromising security.”
So why leave it unencrypted? In case you forgot, the FBI had managed to break into a suspect’s iPhone using security flaws it had discovered (or paid third-parties to discover). By sort of “exposing” iOS this way, it would encourage more developers and security researchers to look into iOS in hopes that more security flaws could be discovered and made public, which in turn lets Apple fix it and also prevents law enforcement from hoarding the information to themselves.
This opinion is shared by Jonathan Zdziarski, an expert on iOS security. According to Zdziarski, “Opening up the OS might help other researchers to find and report bugs, by giving everyone just as much visibility as an advanced and well-funded research team might have.”