All life will be destroyed regardless. We know that there are countless parallel universes (TNG:Parallels). If Charon in one universe can destroy life in the entire multiverse, then there are also some universes in which Discovery did not destroy Charon, and Charons in those universes will proceed to destroy all life in the multiverse. Game over, man!Wait, didn't the Discovery destroy the Charon to save all life in the multiverse? If Lorca hadn't brought them to the MU, all life would have been extinguished. So if they reset everything, won't that destroy all life?