Yeah, I too thought it was open Sunday mornings. But you are right, it is confusing! Since it's an "after hours" club, the idea is to be out Saturday night and you just can't bear to go home, so you go and get your party on at one of these clubs.
I was wondering if there were others, though. You know, like Insomnia or the Lizard Lounge. I know Insomnia closed down, but it was similar. I am not sure if the Lizard Lounge was open, or if there is a whole other club that might have been open. It would be worth checking into people's sm and see what clubs they liked or were into. That could be a clue.