the situation with the Federation during the Dominion War was much more desperate than it was during "mirror, mirror."
It's kind of like Sisko in ITPM. If you're going to try to be ethically pure while fighting a war for your very survival, you're going to lose. Every democratic power has done unethical things for a greater good during war.
Keep in mind that I think that the case for removal would have been clearly justified even WITHOUT a war going on, but it becomes much more so during the Dominion War. Insurrection presents such an absurd scenario of Picard's supposed "idealism" during a major war that it loses any touch with how a government would act during war.
1) This is all based on the assumption that the war is still going on, which we don't know because we don't exactly no when the film takes place.
2) They need dilithium less than in Mirror Mirror since they can just re-crystalize, hell they can probably replicate the stuff now.
And as for deuterium if we go with the Star Trek version I don't think there would be conflict with the Ba'ku since its found on what is basically Hell in planet form (aka why they call them Demon Planets) so they would either be crispy corpses or a life form that is native to that kind of planet.
And of their native to it then like the Tholians (the only race shown so far that would probably survive in that kind of environment) unless their in that environment they shatter.
So unless the feds have more planets available like said hell world they're risking committing genocide.
And we can go on and on about whats necessary for a nation to survive but genocide especially of innocents will never be justified EVER.
So I'm not seeing how the movie works from starship fuel being the central conflict driver since it doesn't ecalty work in the TNG era of the trek verse.
they were removing the Baku, not killing them. Unless you mean that the Baku simply dying of OLD AGE once they're removed is equivalent to genocide.
But then you were so casual about the SON'A dying of old age, weren't you?

Why aren't the Baku guilty of it for exiling the Son'a to die slowly?