Agreed. I had the same thing with my WH last fall on one play, where I flagged the guy in motion for a false start because he cut upfield before the snap (his foot was in the neutral zone before the snap) and killed the play. My WH said that was illegal motion and signaled it as such. At halftime, he admonished me about it, saying the guy in motion could never commit false start, only illegal motion. When I mentioned his foot was in the neutral zone before the snap, WH said it don't matter, still illegal motion. My U pulled me aside later and said, don't sweat it, because they both (false start and illegal motion) have the same penalty, just the difference is live ball/dead ball.