Star Trek: Voyager saw Kathryn Janeway handle the Tuvix-situation correctly.
To have this debate, take out any arguments that fall on the writers. No, “well they could’ve written it differently”. The episode is in the can, it exists as is and you can’t change it. Assume they couldn’t. Whatever defense or point of contention, just assume the ship and crew couldn’t do that thing. So with that in mind, when it comes to Tuvix, Kathryn Janeway didn’t murder anyone. She merely rescued two of her crew. Too often people want to forget that aspect of the episode when talking about Tuvix and the events at hand. Too many people want to say that Janeway murdered Tuvix for no reason, not that she ended a sentient life to save two of her crew. Saying she murdered Tuvix is not true at all, not in the definition of the word murdered, nor in the essence of logic.
Part of the reason people say this is to further a false narrative that Janeway is somehow an evil person, or that she’s incompetent. Inaccurate accusations are levied against her for being a war criminal often from people who misrepresent facts of the series. The argument surrounding Tuvix is no different.
Janeway was trapped on the desert island of space, alone with just her crew, against forces she shouldn’t understand. She did the best she could and in any real-life instance would be rewarded for it. She never committed a war crime because 1. Starfleet was never at war, and 2. War crimes are not universal and cannot be copy-pasted onto any instance.
So why are we talking about Tuvix you might ask? Well, SyFy Wire did a recap of the episode and the host seemed to have some strong feelings about Tuvix as a character and hated the way things shook out. So that inspired this defense of Janeway and her decision-making skills with regards to Tuvix.
It should be noted that the whole “try and save all three” argument is pretty hollow, considering most transporter issues are often malfunctions that just happen with no real rhyme or reason. So splitting everyone like Thomas and William Riker just isn’t logical. The host does blame the writing for the issue with Tuvix, however, so he at least isn’t dog-piling on Janeway. So kudos.
Here are the reasons why Janeway was in the right about her decision to handle Tuvix.