Well if we are honest, Lucas was not the only person from the production crew who made stuff up.

For example at the peak of Lucas hating era, Kurtz tried to exploit it to make himself look good. In an interview he went on about how he left Star Wars because he didn't like Ewoks and the direction Lucas was going with ROTJ. While in fact he was removed by Lucas during ESB production and replaced by Kazanjian.

Another example, in his interviews Kershner always told this story about "I love you" "I know". He stated that they were repeating "I love you too" over and over again and that he didn't like it and then Ford just said the new line at some point. While apparently Ford was the one who didn't like it when reading the script and came to Kershner before they shot the scene with "I know" suggestion and then they did it.