No, this is the wrong approach. The object is not to define personhood through some objective set of criteria which can then be used to justify evil; it's to us

No, this is the wrong approach. The object is not to define personhood through some objective set of criteria which can then be used to justify evil; it's to use our observations about the world to arrive at a broader and more humane outlook. The argument itself is wrong as well. If some method X is used for evil, it does not mean X is intrinsically evil. This is essentially the same flawed argument that's used against many areas of science.