If you were writing a Java application, would you do your own DNS resolution, or would you make a new socket address object and give it a hostname and let the api resolve the hostname for you? If you don’t hand roll your own dns protocol lookups, how do you know the OS, or Java or your socket library aren’t intercepting and modifying request out from under you? Heck, even if you use getaddrinfo directly how do you know your libc implementation isn’t intercepting and modifying the lookups on you? If the threat model you’re coding for is “Apple is a hostile actor intercepting and modifying dns queries” then you really can’t trust their provided posix calls either.

I would feel far more concerned that an arbitrary application that decided to do its own DNS resolution would be doing so for nefarious reasons, or might mess up the process (such as not supporting encrypted DNS in this case).

If you genuinely cannot trust the OS vendor, you don't try to tinker around in user space but you stay off their platform. Personally, this is why I don't have any machines with a Microsoft OS, and why I don't have a Playstation.

But you are already on their OS, so they would always be able to do that. They make the kernel, the hardware and it's firmware, so it's a moot point and needless paranoia. Might as well use the API that gives a better user experience.