User blog comment:B214/Question and Answers 6/@comment-24098614-20161123200843/@comment-9595671-20161125040334

Oh yeah, things would have been much worse otherwise. I even worry that if Rizevim had essentially 'become' Trihexa, then the leaders' plan to seal him wouldn't have worked.

If Rizevim knew how to break Trihexa's seal in the first place, then he'd likely just be able to break the seal they place on him afterwards. They would have truly needed to kill Trihexa, and that would have required calling Great Red for help.