> I tried making a Framework build of Python with the environment variable removed entirely, but I'm not experienced enough with builds on a Mac to know what I need to do to create a proper build.

Given Jason's comment above, it's probably best for one of the Mac-expert committers to remove the environment variable altogether from Mac/Tools/pythonw.c:main(), and confirm everything still builds and runs OK, and then for Tim to confirm that Homebrew isn't adversely impacted by the change.