You mean part of a single episode.
No. They kept her around like she wasn’t someone who should be imprisoned for life, far removed from any position where she could manipulate others.
If they wanted to help others, there was a universe full of people more deserving. Two, even.
Not to mention the fact you say after TNG that the older style was dead as if Voyager doesn’t exist.
Yep.
Seriously, because she’s from a different universe, her actions of committing genocide and torture across any number of star systems are irrelevant?
If Starfleet doesn’t care what people do “in their own space”, how could they ever have a problem with anything? Just declare yourself a ruler, obviously democracy doesn’t play into it, and you decide what you can do anywhere you are.