Then this weekend, he appeared to change his tune.
So… could Warner Bros. plans have shifted in the last few months? And how far along are they in putting their Justice League movie together?
Well, according to Hit Fix, pretty far – as they've already set Joseph Gordon-Levitt to play Batman.
This early booking might mean they're looking to have him appear, somehow, in Man of Steel.
It might also mean that the Justice League Batman isn't Bruce Wayne.
Apologies to those who have yet to see The Dark Knight Rises, neither of whom aren't reading this story anyway, but – spoiler alert – the end of that film is a pretty strong implication that the John Blake or Robin character is about to take up the mantle of the bat.
Is it this character they're setting in place for Justice League? Are they making the film a sequel to Christopher Nolan's Batman films?
Or is this just a slightly confusing move born out of the studio's love of Gordon-Levitt and the strong fan reception to him being a new Batman?
This rumour would have us believe it's the former, as Hit Fix also note that "at least one other actor" from Nolan's Bat films is being recruited to do "something."
Perhaps we'll find out what's going on in Man of Steel, perhaps during or after its end credits. Perhaps we'll find out sooner, if Warners really do get Justice League in motion as quickly as they'd like.
I really do hope that this isn't some fake, studio leaked bunkum designed to promote next week's Dark Knight Rises DVD and Blu-ray release. Seems like a long shot, but crazier things have happened.
UPDATED: Gordon-Levitt's reps have a thing or two to say about these rumours. Exactly what is not clear, but…