I apologize in advance for any errors, this post was written using Google Translate.

Now to the topic. Why did Spirit decide that Soul could become a kishin in the foreseeable future, if to become a kishin - you need to absorb the souls of good people? Yes, Soul's blood was mixed with black blood, but is that a valid reason for such radical conclusions?

maybe it's just an artistic device: intrigue, all that; but still, I'd like to believe that there is a more reasonable explanation for this