I don't buy Walters speech about consequences and God punishing you for over stepping your place by using science. There wouldn't be any reason for Peter Wellers character to feel bad about what he did, in the end his method would have resulted in no one dying and he would be able to have a live with his love. Maybe its just the guy in me but I'd rather have my time travelling girl friend pull me out of the car rather then just tell me that she loved me
Plus I kind of felt that it was out of character for him to do this, he clearly didn't believe in a higher force.