Not to cast dispersions, but could an empty cavern photo have been taken during original construction, photo-shopped, the result of a curtain, or in some other way not realistic? Again, sitting here, I have no idea what is correct due to my lack of firsthand knowledge in all these regards. Personally, I don't recall a photo of an empty cavern, but I sincerely wonder if it would stand up to scrutiny if indeed it could be found.
My skepticism is based on the utter absurdity of disconnecting and hauling out that behemoth, only to shove it back in for no apparent purpose. Yeah, there might have been some logical reason for such shenanigans, but the whole exercise seems like an awful lot of work for very little result.