I believe the clinical term is "binary clone" and that is a real thing. Look it up.
But this is the fundamental problem here. It was not a clone, nor was it a child. It was the accidental combination of the DNA of three separate entities, and far more importantly, a combination of two separate, unwilling entities.
It had no claim to own those separate consciousnesses, it had no right to exist at other's expense. This is the point in it's entirety, and one you seem to be ignoring. It did not have the right to exist at the expense of Tuvok and Neelix. If it had been born, it would have the right to it's own self, but it was not.
Janeway did exactly the right thing. Her responsibility was to Tuvok and Neelix. Not to an aberration created by accident. At a time in history when accidents like this CAN happen, the rights belong to the accident victims, NOT the aberration. This is a reasonable interpretation, considering Tuvix to be same as Spock is not. This is the second thing you seem to be ignoring.
And, debates get heated. The fact that a debate gets heated is not a reason not to engage. You don't fool me. You don't have an argument to defend.