While we're on the subject, it might be worth summerising the instances of left-handedness amongst the Muppet puppeteers themselves. Here's a list of the ones whose names seem to "demand" to be mentioned:
Terry Angus - Honory Leftie. Writes right-handed, but happens to puppeteer left-handed.
Anthony Asbury - Someone said a while back on an internet discussion that he might be ambidextrous, since they saw some footage of him puppeteering that looked as if it was puppeteered left-handed. But there is also definite footage of him puppeteering right-handed. So we don't know.
Fran Brill - Right-handed, the picture in JH The Works was flipped.
Richard Coombes - Left-handed and puppeteers that way.
Dave Goelz - Puppeteers right-handed. Some unconfirmed rumours that he may write left-handed. But no one here seems to know.
Louise Gold - Perhaps the best known truly left-handed puppeteer. She is Left-handed and puppeteers that way.
Jim Henson - Not left-handed, there was a myth that he was, but he wasn't. There is a lot of film footage that clearly shows him puppeteering right-handed, and some film footage showing him writing or drawing with his right hand.
Jerry Nelson - Right-handed, but for a couple for years there was a period when an injury to his right shoulder forced him to puppeteer with his left hand, he never liked it, and as soon as he was able to do so switched back.
Mike Quinn - Lefthanded and puppeteers that way.
Marty Robinson - Writes with his left-hand, but puppeteers right-handed.
Hope that is of interest.