I agree that cloning is morally wrong, but not because of principle Q. First of all, I think that reproduction of human is different from reproduction of plants, because generally human reproduction requires combination of sperm and egg. However, cloning just requires DNA from a cell from scalp tissue of one person and I don’t think cloning follows natural law because it simply extract some DNA and produce a very similar “human-alike” product.
Also, I think cloning is different from having babies without genetic testing for diseases. Some people will have pre-marital medical exam before having babies, but it is not for sure that the genetic disorder will pass to next generation. Thus, it is hard for parents to abort babies or change other mates. However, we are hundred percent sure that cloning would shorten animals’ lifetime. It is immoral to make worst choice if you have other choice available.