His jaw twitched at the question, but he just nodded, at the news of her being with a sitter. "That's probably best."
It probably showed in his posture, that he was poised to follow after the Fallen, but he was intentionally holding himself back. He understood, probably better than Aziraphale, that neither of them were as unchanged from this as they appeared. And for the moment, he was just selfish enough to need the denial, to feel as though the Angel had simply gone to talk to his friend, and nothing more.