Remove Unused is a great concept! I found a bug in 1.2 (running MM3). The confirmation screen showed as expected for mood, occasion, quality, and tempo.
However, when the confirmation screen for genre came up, it was very long (120!) and I couldn't scroll the window or move the top off the top of my screen so that I could see the bottom and click ok. I think the script operation will work properly, but could you fix the window so that I can see to the bottom if there are many genres?