From personal experience, that's a proper reading of the rule. You can do things for "personal education" but you can't release anything that's code (open or closed source, doesn't matter, including things already released...you can't maintain them) or code-related (e.g., blog posts, books, etc.) without a ridiculous number of approvals (some from people at like the VP or SVP level).
Author here. I've heard from current and former employees that they believe that Apple doesn't actively police it. However, telling people not to makes it easier to shut down later if they want.
Thanks for writing such a fantastic tool. It's recently become for me a must-have when writing shell in any codebase.
One thing I've really appreciated is the Github wiki pages for individual shellcheck errors. Without those pages I wouldn't have learnt so much more about shell and the shellcheck tool would be more difficult for people to use :)
It is possible to get an exception approved by SVPs -- legal/general counsel merely advises management after all. But Shellcheck's GPLv3 license is a virtual dealbreaker.
Really, really expensive lawyers I would guess. I look to Apple's behaviour towards the Right to Repair movement for proof of past behaviour/culture as an organisation.
I can speak from personal experience that it's happened, though it's unclear if the violation of this rule was the real reason for the termination or just the scapegoat.