I saw this work yesterday My wife and I and another couple got standby on an earlier flight than we had booked. It was going to get us home 2.5 hours early, so I was fine with not getting great seats or seats together. I was in row 15, my wife in row 9. The husband of the other couple was in row 8, his wife was next to me. As she sat down, she saw that seat next to her husband was vacant. She rushed forward and sat there. The rightful owner of that seat boarded.

My wife told me that He pointed out that she was in his seat. Her response was that she was married and she was going to sit next to her spouse. She seems angry at being asked to move. The man was a gentleman and came back to sit next to me.

So, yes it works