They have two normal hands which are (as all normal hands are) mirror opposites.

The point being that a symmetric controller design makes sense for people with symmetrical hands. (And that asymmetric controllers do not (which is correct))

lol, ok - so they're being cheeky and describing having two normal hands in a strange way to uh emphasize the symmetry? Confusing but kinda funny if that is indeed what was being expressed.

When I point my thumbs to the left the palm of my left left hand is facing up, but my right left hand is backward and when I point the thumb to the left the palm faces down. It's very inconvenient, really, not only do I have two left hands, one of them is backwards. It's a wonder I can even type.