Mostly, the BSD people think that POSIX and ISO C are just forks of Unix documentation, that are mainly used for making non-Unix systems look Unix-like. BSD comes from real Unix DNA and so following those is optional; whatever direction BSD takes is Unix by definition, as if it's forever 1983.

Interesting. I wonder if that means BSD's compiler toolchain has ignored the strict-aliasing misfire that makes such a mess of the ISO associated ones.

"BSD compiler toolchain" is just a GNU toolchain that is a decade plus old.

It will be probably twenty years before someone programming on BSD will have some code wrongly deleted as unreachable because it comes after realloc(ptr, 0).

They are immune from the damage.

For instance, OpenBSD 6.8 was released in 2020. On that release, gcc reports as 4.2.1, released in 2007.