ya, if you can't go on it...well, that's just wack! When i was there in early September they were removing the previous exhibit from that space...who knew they were gonna turn it into a super-slide space!?!
In fact, at PS1 in Queens, NYC some years back, there was an orange plastic "tornado slide" that emerged from the 3rd floor windows in the courtyard and spiraled down to the entrance on the ground floor. You had to sign a waiver to jump into it, but otherwise it was completely accessible. I remember diving into it the first time I visited the museum, and thinking afterwards that PS1 was the coolest art museum in the US for having a tornado slide.