Despite insinuating that the man in the distasteful costume deserves to be bitten by a bloodthirsty rabbit, Aziraphale is actually quite surprised when Moloch darts out of the hat and returns shortly thereafter with a bit of that blue fabric in his mouth. He picks up the torn cloth and looks between it and Moloch, clearly unused to anyone standing up for him, aside from Crowley.

"Thank you, dear. That was..." Well, he knows better than to say 'nice' or 'kind', especially because it wasn't really. But it does clearly mean a lot to him. "...an appropriate level of retribution."