I must admit even in my relatively brief time here at trekbbs I have read the various arguments explaining Tuvix. My personal understanding comes from the transporter aspect too. When individuals are transported their presence - clothes and all is reformed from one station to another. There are only ever those molecules at play. I suspect the plant was more like a chemical catalyst. However Tuvix was not a child born of two parents. That parallel never convinces because he fully replaced two individuals. He was a mashed up, compacted being made of their 'molecules'. They remained existent, within him, they were him. Once the transporter anomaly was fixed it enabled the original action of transport to be completed as was intended resulting in Tuvok and Neelix taking their forms as was their right and expectation and their priority. Whatever freak transient existence Tuvix had was always a placeholder until (and if) the norm was returned. Tuvix was a parasite to two hosts.