This sounds to me as though he was looking for an excuse to shelve it anyway. Maybe he got to a certain point in the process and thought "Nah, just not feelin' it." That's just a guess on my part, but it feels true anyway.
It's a media whore & money making gambit, plain and simple. He gets to make another blip on the media radar screen, & sales of the book will skyrocket because "Don't you know? This is the Tarantino project that got axed becauszzzzzzzz..."
@1 it's fascinating to read scripts in general, for plays, films, TV, and comics, to see how much difference there is from one end of production to the end product. Its like when you see some of these films, and you think--how in the hell did this happen? How did this turn out so terrible? But you read the script, and it's like, wow, that was actually halfway decent at that phase. It was that the execution sucked somewhere. Plus it's fun to see the craft of the artist at work on that different level.