Safe, Secure, and Secret
Wayne was in the yard day in and day out. He knew how this looked to the neighbors, which is partly why he kept quiet. It was fun that he was the talk of the town. He was giving people something to gossip about and look forward to, which wasn't a part of the plan but just made things more exciting.
Wife Approved
The neighbors tried to extract some information from his wife. She was supportive of his choice to be sneaky with it, so she didn't reveal much of anything. She did make it clear that she was for his decision to build his secret room underground and thought that it was fun and useful...