Aziraphale has the notecard in his hands before he has anything to say about it, he stares at it, then at Crowley.

"--are you bloody mad? I'm not leaving you here by yourself." There's anxiety in his voice, sure, but quite a lot of assertiveness.

"And there's all these mortals here, we can't just--we can't do this here."

Because, you see, Aziraphale might think himself soft and a coward, but he's not letting Crowley to fight alone.