I don't buy it. Yes, the language may be C, but if you're linking the ObjC runtime and frameworks, all you're really avoiding here is the nib-loading machinery.

To be fair, I think that's a perfectly reasonable goal in and of itself - showing how to set up an OS X app "from scratch" is definitely something I'm interested in - but we shouldn't pretend this isn't strongly relying on Objective-C to actually get things done.

EDIT: indeed, the makefile copies main.c to main.m before invoking clang, which means it's using the Objective-C compiler.

What would be much more impressive is if this used only the C Core* frameworks (Core Foundation and Core Graphics in particular) to do the same thing.