I suppose we could look at it as manipulating, but, what is to be gained by that. What would be the sense of changing the numbers for only a few minutes while people watched the parade and be back to regular lines again. People didn't walk up to the ride, look at the wait time and decide to watch the parade instead. In fact, it was the opposite for me. I felt that the lines would be shorter during those activities, but, since getting a fast pass for it was close to the same thing as parting the Red Sea, I decided to bite the bullet and get in line. I was rewarded for my decision. But, for Disney, fudging the times has absolutely no benefit other then making people like myself feel better because it didn't take as long as it said. When we do get upset is when it says it's 45 minutes and it is 90 minutes in reality. Something that used to happen on Soarin all the time.
It was a walk-on because people were watching the parade/fireworks, it wasn't a walk on because it said 45 minutes. It is cause and affect. 20 minutes strikes me as a normal time it would take for any ride that was just a walk up in a relatively long queue area and just confirms that it's the other activity that shortened the wait time. Save the manipulating for FP because that is what FP is. Putting people in predictable places and spreading out the levels.