Genocide and slavery as jus cogens norms?

In a post below (or see here if you came from another link) I dealt with minor typos from Chapter I of Public International Law, 2006 Edition by Ruben E. Agpalo. Here we see that Agpalo seems to say that genocide, etc., is the norm under jus cogens.

Take a look at this paragraph from page 10 :

Wow!