Apple is a company, not an operating system. The parent is almost certainly aware macOS is BSD-based and is suggesting Apple also uses Linux in e.g. cloud deployments. They are of course correct.
The "higher" levels of XNU are largely inherited from the BSD legacy, but we're clearly talking about what serves as the base. So even if you take an inheritance angle, XNU is based on Mach, not BSD. macOS is full of BSD/derivatives code, sure, but it is not based on them. The foundation is laid elsewhere.
> No, you just switched usages of the word "base" mid-conversion
The original assertion was: "Apple is BSD based". While we did move to assume Apple means macOS (iOS, et. al), we stayed the course with the remainder. There is nothing about macOS that is BSD-based. Containing some BSD code does not imply that it is the base. macOS also contains curl code. Would you say macOS is curl-based?
Regardless, what you may have missed is the additional context the followed: "not Linux". The parallel to Linux in macOS is XNU. Therefore, if other systems are Linux-based as we are to infer from the original comment, then macOS is XNU-based, not BSD-based. Yes, XNU contains some BSD code, but it is not BSD. It is very much its own distinct kernel maintained independently of BSD-adjacent organizations.
> This conversation isn't advancing anyone's understanding. It's just pedantry.
It could advance someone's understanding if they were open to seeing their understanding advance. I understand not everyone is accepting of new ideas and that many fear learning something new.