Open and shut case?

What do you think of the psychology behind the jury's reasoning in this story I found on the Futility Closet blog?

A man’s wife disappears, and he’s accused of killing her.  At the trial, his lawyer tells the jury, “Ladies and gentlemen, I have amazing news.  Not only is my client’s wife actually alive, but she’ll walk through that door in ten seconds.”

An expectant silence settles over the courtroom, but nothing happens.

“Think about that,” the lawyer says.  “The fact that you were watching the door, expecting to see the missing woman, proves that you have a reasonable doubt as to whether a murder was actually committed.”

He sits down confidently, and the judge sends the jury off to deliberate.  They return in ten minutes and declare the man guilty.

“Guilty?” says the lawyer.  “How can that be?  You were all watching the door!”

“Most of us were watching the door,” says the foreman.  “But one of us was watching the defendant, and he wasn’t watching the door.”

Makes sense to me.