In addition to being a coward (saying 'You will' after supes flies away, and not directly to his face), this batman is also a fucking hypocrite.
He's ready to destroy Superman, but somehow the Joker is still alive and kicking. This movie just makes it looks as though Batman is just jealous of Superman's powers.
I think that insecurity is a big fuel for him in this movie, yes.
But, even with that in mind I think Batman isn't exactly a coward for asking Superman if he bleeds to his face and then speaking at a volume he can clearly hear, right?