Here is a plausible explanation for this (based solely on my speculation):
Geffen/Interscope, repeating a tactic unsuccessfully used in 2004, tell Axl GH2 is coming out b/c CD has not been finished yet. Limited promotion begins (such as placement on Amazon's site). Slash, as a co-owner of GN'R's back-catalog, is informed. Slash is later informed that GH2 is cancelled. Naturally, he questions why. Geffen/Interscope tell him...
Again, this is based solely on speculation. But it is plausible. It is also plausible that Slash is talking out of his ass.