Sabretooth is a monster. No question about it. But I think Magneto set Sabretooth up.
Magneto is a really really smart guy. Yeah, he gave Creed orders, but Magneto also probably knew ahead of time that Creed was incapable of not killing. Did Magneto include Creed on a mission so that he could eliminate a loose cannon, someone who was sure to stir up unnecessary trouble with the humans? Or, did Magneto use Creed so that he could later make an example of him? Or both?
Or, am I reading too much into this?