If that is truly the case which I doubt then Apple has some larger issues in the OS it claims that is so secure. At its core iOS is unix which is a fairly secure OS in how it can sand box most things and prevent leaving the sandbox.It's about code execution outside of Apple's control. If a developer is permitted to execute any code they want, we're going to see a lot of abuse and potential device compromises.
I suspect this might be why BrowserEngineKit will be limited to iPhone... because it's Version 1.0, and they want to limit the scope of any such abuse, bugs, and user confusion.
Apple is doing malous compliances and everyone knows it.