As far as I can tell, it's not like he's shutting down an active production and putting people out of work, he's simply chosen not to develop a script he'd written because some bugger leaked it.
I think it has less to do with spite than just plain irritation. But that's neither here nor there. It's his script, his movie and his choice whether he wants to make it or not. Though I don't like to presume to speculate on another person's rational, I imaging the whole thing would now feel somehow tainted and he's probably just lost all passion for the project.
It's not like he owes anyone this movie and it unfairly depriving them of it out of spite. It's just a script and like he said, he's got ten more where that came from.