Book titles, unfortunately, cannot be copyrighted.
You took the words out of my mouth. For some reason I have never understood, book titles cannot be copyrighted. It's common to recycle old titles.
On the other hand, this is still an insult to a fine writer. He should have had the courtesy to at least try to clear it with Bradbury. Moreover, it's not as if the title really makes much sense for the movie; in that regard, it's a pure ripoff of Bradbury's original, with which Moore hypocritically pretends to have some sort of concern for free speech.