I am not conflating anything, and you saying so doesn't make it so. Maximum acceleration from a catapult is the point at which the forces are the greatest in any such trajectory. Maximum g forces are transferred to the payload at the moment of release of the stored energy of the catapult. When the person tried it, he did not know if it was going to injure the animal. A normal person would probably experiment with their creation by loading it with a jug of water or a bowling ball.
It was funny when monte python shot dead cows over castle walls, but the cows were not real anyway.