Antagonist: If my ideology is enacted, everything will be better!
Liberal Protagonists: oh fuck how will we deal with this, I have no arguments to defend the status quo
Antagonist: just kidding, all that ideology was a trick, I'm Just Evil™
And then they can kill him without thinking about anything at all. Happens all the time.
Off the top of my head is legend of korra (I know im 2 weeks late for that discourse) the Black Panther movie, and even Pokemon Black/White have the same themes
Liberalism is about the status quo, at all costs.
I remember reading somewhere that it was tricky to write science fiction in the Soviet Union because the assumption was that they were eventually going to achieve communism, and that all alien civilizations would inevitably be communist, so you had to think outside the box to come up with interesting conflicts. Probably less of a problem from thje 60s on, if it ever was.
Check out archeologies of the future by frederic Jameson, it chronicles the difficulties and different conceptions of how to write utopian science fiction.