Even if from this you decide not to kill pigs, the Bayesian spam filter that keeps dozens of viagra ads per day from cluttering up my inbox is also undoubtably learning. Learning, indeed, in much the same way that you or I do, or that pigs do, except that it's arguably better at it. Have I committed a serious moral wrong if I delete its source code?

If I were programming an AI to be a perfect world-guiding moral paragon, I'd rather have it keep the spam filter in storage (the equivalent of a retirement home, or cryostasis) than delete it for the crime of obsolescence. Digital storage space is cheap, and getting cheaper all the time.