Are you really really afraid to be deemed "phony" if you leave the keyboard and let it play on for the benefit of the audience? Look mom no hands!!! DO you think the audience is that stupid to believe you are playing all those parts? Surely not.
you would be considered a "phony" because you clearly see others in that manner. That's too bad because being glued behind a keyboard that's playing most of the parts by itself would make me as an audience member wonder if you were handicapped and could not get up and use the room to your act's benefit.