If God wanted Noah's arc to succeed it would succeed. God can make the entire universe out of nothing, create life, raise the dead, SURELY he can take a wooden boat and give it a successful journey during the flood.
God, a mass murderer? He gives life, it is not ours but his, so its his to take freely whenever he wants. The living God, he who authored life, the creator of heaven and earth, he who came down and allowed himself to be tortured and crucified so that our sins would not result in our death, our great and merciful God, he is beyond reproach.