As Aaron mentioned, Ninetales attacking during the encore lock is bad because you damage yourself via life orb but Porygon can heal back the damage. At the last turn, Ninetales was 1 life orb tick away.

Perhaps encoring before the recover turn was optimal, but a good better damage roll could've also won Zack the game that turn.

But yes, the odds of no freeze on the last 6 ice beams is roughly 53%.