The reason I ask, if it does involve adjusting the melody, it would seem to be easy to fix. The program could simply not allow any adjustment under those conitions. That's what happens anyway if you don't select "Yes". Number of choruses is still reduced to 1, and the melody remains.
At the very least, a warning message could posted in the dialog box.

(this is assuming that the problem can't be fixed properly for some reason. If it could be, then obviously that is what should be done)

The work arounds are simple enough, but if you are unaware of the problem,
there is no work around the first time it happens.