I'm happy to risk a protest. My state does not allow them.
The penalty for rule 6, articles 1, 2, and 3 states:
"The ball is dead immediately when an illegal pitch
occurs. If there is no runner, a ball is awarded the batter. If there is a runner,
such illegal act is a balk. In both situations, the umpire signals dead ball."
If F1 fails to release the ball, I'd rule no pitch: thus it cannot be an illegal pitch. If he does release the ball, 6-1-4 applies (ball if it crosses the foul line, otherwise no pitch).