Because he doesn’t seem entirely sure. Maybe someone at Warner Bros doesn’t like it as much as he does.
Anyway, here’s what he had to say: “The movie, I think, is going to be called The Batman. At least that’s what we’re going with now… That’s about it right now. That’s all I got. We’re working on the script, the script is going well. I’m really excited about it, and I assure you that when there’s anything that develops you’ll hear about it.”
Wonder how long it took to brainstorm that one?