This might surprise you if you know anything about babies, but there's no consequence for drowning Baby Moses. You can go back to the beginning of the level and get a new baby any time you want. Your only mission is to get him to the end of the level, but if you beat it without him your only reprimand is, "GOOD WORK! BUT YOU FORGOT BABY MOSES!" That's it. No one screams, "Not only did you fail, you killed Moses 94 times! What's the matter with you!?" So even if you kill Baby Moses, you still feel pretty good about yourself. And I'd like to think that's exactly how Baby Moses would want it while he was sitting on the bottom of the river getting eaten by spiders?