So what are you hinting at? That by your definition of "human" the message of the comic is wrong and a majority of humans is evil? What do you classify good people then? Angels?
I think they meant that often the out-group is defined as non- or sub-human. So technically they believe all humans are trustworthy, kind and peaceful, just not those in the out-group, but they're not really humans anyway.
Do companies count as people? Companies do evil things. Do governments count as people? Governments do evil things. Do religions count as people? Religions do evil things.
ALL of these are made up of people yet do overwhelmingly evil things, how do you square those two perceptions?
For A City on Mars, I read a lot of war theory, and one of the interesting things was how almost everyone stressed immediately that most places and times are peaceful.