That episode is great because I know we can debate this until we’re 100 comments deep, so respect to the writers for sure!
I don’t think that’s a fair comparison. They’re dead, why should they get to consent?
The only reason to bring them back is sentimentality, Tuvix was more than adequate to be chief tactical officer, but he wasn’t Janeway’s friend of 20 years anymore.
There was a time where I think Tuvix would have agreed to the separation, but he had built enough of a life for himself that he didn’t want to die, and I don’t see how Tuvok and Neelix’s hypothetical rights supersede Tuvix’s very real request to live.
Would it have been fair to kill Tuvix 20 years later? As Janeway said, when did he go from being a transporter accident to an individual?