You know how people say, "he's not really dead as long as we remember him". They actually say that, not just in the movies, people say it with great feeling and it is a meaningful part of dealing with a loved one's passing.
Well no one EVER on their deathbed or dealing with a terminal illness comforted themselves thinking that they wouldn't really be dead because after their heart stopped and their brain went dark their relatives and friends would still be sitting around reminiscing about them.
The whole episode is full of these little tricks and the Tuvix threads are full of these little tricks and in the end Tuvok, Neelix, and Tuvix all either existed or they didn't.
Well no one EVER on their deathbed or dealing with a terminal illness comforted themselves thinking that they wouldn't really be dead because after their heart stopped and their brain went dark their relatives and friends would still be sitting around reminiscing about them.
The whole episode is full of these little tricks and the Tuvix threads are full of these little tricks and in the end Tuvok, Neelix, and Tuvix all either existed or they didn't.