That's interesting! But confusing as well. The test they reference (https://en.wikipedia.org/wiki/Psychopathy_Checklist) includes lack of empathy. Are they saying that this criterion could be dropped from the test with no effect on the classification?

How I understand the article, is that they understand why others act in certain ways, they know the mechanism of empathy, but nothing here confirms that they are empathetic themselves. I think this article's conclusion is misleading.