Peter Singer is the same guy who believes killing infants should be legal because they're not persons. Says he: "In Chapter 4 we saw that the fact that a being is a human being, in the sense of a member of the species Homo sapiens, is not relevant to the wrongness of killing it; it is, rather, characteristics like rationality, autonomy, and self-consciousness that make a difference. Infants lack these characteristics. Killing them, therefore, cannot be equated with killing normal human beings, or any other self-conscious beings."

In this op-ed, Singer simply applies the lack of 'human qualities' to individuals and groups and ideas he doesn't like, and can therefore justify violence (murder) as a means of addressing those groups and their ideas. 

Singer is a Sangeresque progressive, and has a lot more in common with Nazis than do half-wit 'white supremacists.' It was Sanger who inspired Hitler's Nazi regime to use forced sterilization as a means to control 'troublesome 'populations.