Why does General zaroff do that makes rainsford uncomfortable

After Zaroff reveals that he hunts men, he then proceeds to try to convince Rainsford that what he does is not problematic. As he explains it, his sport only mimics the natural divide between the strong and the weak that is found in nature. In addition, Zaroff explains that he hunts what he believes are the scum of the earth. Rainsford doesn’t believe that this is a valid point because they are still men, regardless of what they have done.