John opened his mouth, then shut it again. The stars? The stars. He tried very hard not to pass judgment, but he was only human. It sounded mad, and given that they were in a madhouse, a very simple solution was there for the taking.
So, Watson went for the noncommittal answer. "I haven't seen the stars here. There was a bit of trouble in London and then I woke up in a hospital bed." It was truth, and he wasn't left in the difficult position of having to comment on the substance of Zoe's claims.