Sorry I don't have a link, but either Leon Vitali or Jan Harlan was interviewed a few years ago and discussed burning outtakes from Eyes Wide Shut, per Stanley's instructions
. I can't remember if the destruction of footage from other films was mentioned.It seems odd that Kubrick would single out EWS only, as the reason IIRC was that Kubrick only wanted his final vision of the film seen...so it would make sense that this would apply to the other films.
I'm not disputing what someoen said earlier in this thread about Harlan's quote, just relaying what I've read.
I used to follow the Kubrick NG pretty closely, and I don't recall a single thing about rare footage from 2001 being in collectors' hands. I think this would be far less likely than someone coming forward with a copy of a SW 70mm print, for instance.