I think the more honest way to say this would be: "variable framerate somewhere between 30 and 60fps". Framerates can be capped at factors of the refresh rate, such as 30fps or 60fps, in order for there not to be any irregular judder to the frame delivery, but they can't just be magically locked at a framerate higher than the hardware is able to perform.
Therefor, it makes no sense to talk about an unlocked 60fps because that would imply framerates above 60fps, not below. When it is really running mostly in the 40s or 50s it doesn't really make sense to call it a 60fps game of any kind.
Anyway, I've heard from people that have the game on the PS4 that it is actually capped at 30fps anyway. Can anybody confirm this?