It's not the norm for the zoos in Arizona. Very, very few animals are off exhibit. I think the only ones that are belong to educational shows and those are mostly birds and tortoises and the like. We had Sand Cats years ago and they were kept in an out of the way exhibit, which seemed to work. Not many people knew they were back there and you had to go off the main route to get to them.
As for the location being the best place to meet their needs, it's not likely. It's part of the EVENT CENTER. Meaning gobs of people will be able to looks at them all at one time when there's an event and there's a lot of events, particularly at night when the cats will be active so they'll have people staring at them while they're awake. Can't imagine how that would be better for them. The only other facility I'm aware of that has Sand Cats in this part of the world is the Living Desert and according to their map, theirs is on exhibit. I don't know if the Exotic Feline Breeding Center is Rosamund, CA is considered Southwest. If it is and that's the zoo you're referring to, then yes, they keep their off-exhibit. Their main focus at that facility is breeding and they have had great success with their Sand Cats. I've only been there once and didn't remember seeing any, but then I saw they got their first one in 2011, I believe, and I was there in 2010.