It's like calling a newspaper editor useless because he's not the one writing the stories. Or the football coach pointless because he doesn't execute the plays.
St.Clair's actions are enough to break a sweat. Seriously. Post-concert, sometimes conductors like St. Clair look like they just finished the Boston Marathon.
If you don't believe me, check out YouTube videos of the greats — Leonard Bernstein, for example. Take heed at his crying on the job while conducting some emotional Mahler. You'll see dripping eyes and a perspiring forehead.