Based on what rule? Why is waiting with the hands together illegal if the start of the pitch is not until the hands separate?
Rule 6-1(E): The pitcher shall hold the ball in both hands for not less than one second and not more than 10 seconds before releasing it, and both feet must remain in contact with the pitching plate at all times prior to the forward step. Page 66-
According to this rule from the 2011 ASA rule book- once she brings her hands together- her time is limited to begin the pitch- Whether this is actually enforced or not- I can't say. I am just saying that according to THIS rule, her waiting with both hands together for > 10 seconds is not legal.