This is ONLY if the user has installed Apple Update Software (I would imagine most people who use Windows OS probably have it automatically installed if/when they installed iTunes).

I think it allows the user to know that Apple has software that's compatible with their computer, and IF they want, they can download it. To be honest, it really doesn't matter. I think if MS cared about the Mac OS, they would do the exact same thing. But they don't, so they don't.