Trust the Psi Corps.
LRH was a clever dude! I never thought of that. However, he married Mary Sue Whipp, who became his "third" wife, but if he "never had a second wife" prior to her, well, then she would minimally have been his second wife. Thus, by the time of that interview, even if his marriage to Sarah was null, he most certainly DID have a second wife, Mary Sue. No matter how you slice it, he was lying.
I think that is a case of being really pedantic. Yes, Tubbs sounded stupid saying it, but there is a female in my past. I and her ex-husband both refer to her as "Zero" and in a club of which we used to be mutual members she is perpetually called "She whose name shall not be mentioned" with overtones of The Scottish Play.