@lanodan @abbienormal if (UNIX AND NOT APPLE) you mean, but yeah, I see.
I would argue that that is an OK pattern if they really want to single out Darwin (maybe for Mach-O or something), but not quite right if what they actually care about is freedesktop-ish vs Cocoa-ish. You can certainly have GNUstep on non-Apple systems, and run a regular X11 desktop on Darwin.