This is true but hard to argue within the universe as we just don’t have the info and there are in universe contradictions about transporters. Been a while since I saw the episode but for me - ‘nonexistentance’ is close enough to ‘dead’ that Tuvix should have been allowed to live.

Tuvix adds another element though. Tuvok and Neelix were already dead and Tuvix was alive. I think that makes this different from the standard trolley problem - still a hard choice but not the same.