After the recent disaster of the Trekonomics book, it is quite refreshing to see another old page concept I've never followed up on given a much better, albeit brief, look. Timothy Sandefur has taken Star Trek politicial philosophy concepts and examples and woven a narrative that is probably not too far off the mark.
The notion of TNG as a muddled leftist mess isn't quite how I was thinking of it, but I can't say Sandefur is wrong, either. I'm iffy on some of his examples ... Picards refusal to intervene in the Klingon Civil War is interesting, yes, but interventionist versus non-interventionist foreign policy isn't a left/right issue. We've seen war-mongering leftists and isolationist right-wingers, after all. But certainly Sandefur's take is worthy of consideration. His comments on Spock relating to his opinion of Vaal in "The Apple" and the justice of the Klingon peace overtures are dead on ("The Way to Eden", too, but I think it a touch unfair to count that one for much). Indeed, the idea that the peace with the Klingons took a long while after the Star Trek VI Khitomer events actually helps assuage some of Sandefur's indignation.
Speaking for myself, I see a pretty moderate and perhaps even libertarian strain throughout the TNG era, at least operationally, pragmatically balanced with classically-liberal ideals. Compared to leftists ruled by emotionalist whims and logical defense-minded folks who are aware we can lose it all without great caution, Star Trek inhabits that happy place where risking friendship can reap reward under the mantra "hope for the best, prepare for the worst". Modern America should be so lucky with its political leadership.
Of course, by today's media and cultural standards which have broken so far left, one could argue that DS9 looks like Ayn Rand half the time. There are misses and occasional leftist nonsense, but generally speaking the adventures of the Enterprise and friends are wholesome though-provoking entertainment for young Constitutionalists and others who understand liberty.