If this moral imperative was so important, then Kathryn should have gone and ahabbed for Neelix's lungs that were stolen by the Vidiaans in season one and got them back... And further more when Neelix and Kes broke up, she could have asked for her lung back from Neelix which she donated.
How did THE Vidiaan organ black market work any way?
Did the recipients know that they were harvested from the uniwilling and murdered, or did they believe a bunch of lies to keep their peace of mind?
If the recipient doiesn't know that they (two lungs, two recipients?) have to hide, Voyager might have been able to find them with ships sensors scanning Vidia from orbit.
But this is a point that Tuvix should have brought up about how Janeway usually doesn't care whear his organs wind up deposited, hell Tuvix could have made a ruckus and demanded they turn the ship around right now to go get them, since why should have have to die to make an inferior version of Neelix that 's only up to 90 percent of specifications?