Disengagement isn't over!
Pitchers are allowed to seperate their hands during a feint. This is legal under FED Rule 6-2-4e.
It is a balk if he takes a hand off the ball
... unless he ... steps toward and feints a throw ... 3B.
I said it was a good question w/ a very complicated answer.
And where does it say that a "legal" feint doesn't require any arm motion?
Is it written in a FED, NCAA or OBR rulebook?