You need to remember that Apple is a US based company, country which is by far the most litigious in the world. They (Apple, or any other powerful company, for that matter) can bring you to homelessness just by dragging you through courts.
By paying them lots of money and giving them interesting work. Obviously not everyone will make that trade but many will. There's plenty of work done in many areas of industry and government that aren't especially open and most of them probably don't pay nearly as well as Apple.
I recall that was an area of complaint about AI researchers a year or two ago. Valley companies were hiring them away from Academia and little research was being published as a result.
Yes, Siri has much more lenient policies for academic publications than other Apple departments, and other parts of Apple are also getting a little bit less strict. It was never entirely impossible to publish at Apple, but it used to be extremely difficult.
Once it became evident that this was a clear competitive disadvantage in ML hiring, policies evolved…
In comparison, Apple's reaction to a prolific leaker was fairly mild, and left him far from unemployable (I happen to know what company hired him next), let alone homeless: https://www.macworld.com/article/1018725/workerbee.html
