Calling it a backdoor may be correct, but calling it an "OS X backdoor", particularly with no other context in the title, is not. It's merely clickbait.
Yes, I concluded from the title it's backdoor in OS X itself (which would be huge news), not merely a backdoor kit running on OS X (which is not really all that notable, absolutely no surprise that backdoor kits exist for OS X and this one is nothing special among them as it seems).