I would have to disagree with him, at least as far as an R bike is concerned. He may be right on a Triumph or Ducatti about the idle part,
but I would strongly disagree about off-stop operation.

The butterfly is closed at idle (as the manual says you should be able to hear them "snap" shut when adjusting cables), and idle is regulated by the BBS.
Off stop, or partially open throttle is controlled by the cables, so yes the balanced setting is important. You want a balanced firing of each cylinder for a smooth running engine.
This is probably more noticeable on a boxer or opposed engine as it is with an upright twin, or even a V design such as the Ducatti. A boxer engine will run with much
less vibration if they are balanced. This is very noticeable in your rear view mirrors.
I will also add that I went from mid 40's to high 40's to low 50's on mpg. (if I ride sensibly, which I don't seem to be able to do most of the time)