Stuxnet was discovered because a bug was accidently introduced during an update [0]. So I think it speaks more to how vulnerabilities and bugs do appear organically. If an insanely sophisticated program built under incredibly high security and secrecy standards can accidently push an update introducing a bug, then why wouldn't it happen to Apple?

[0] https://repefs.wordpress.com/2025/04/09/a-comprehensive-anal...