Hey! ... I'm not nuts!! 
Well, that remains to be seen.
But that quote from the email makes perfect sense to me: "If you are a Windows user: Nothing to see here, your Windows version is the same as it ever was." If you interpret it the way you were thinking about it, you're ignoring some cognitive dissonance in the statement:
If you're a Windows user, and not a Mac user, we still have something
for you. If you own a license for JRiver Media Center 18, you can download
the latest build free of charge.
If you are a Windows user,
and not a Mac user, then you wouldn't be able to USE the Mac version, so the "you can download the latest build free of charge" part obviously cannot refer to the new OSX version, but refers to a new build of the Windows version you had before. In other words, that statement just meant: "Don't worry, we aren't switching to become a Mac-only development shop. We're still working on Windows MC at the same time."
Though, I can see why you might have been confused by that, I suppose. Mostly it was just excited, though.
In any case, the MacOSX version of MC is licensed separately. I think that's totally fair. It's a massive project.
