What this points to is a certain commonality, at the very extreme ends of the spectrum, between left-wing critique of “American empire” and right-wing isolationism — a foreign policy variant of the “horseshoe theory” of political ideology, which posits some factions on the extremes are closer to each other than those on the center-left and center-right.
The left-wing variant starts from the idea that America has evil intentions for the rest of the world — that it is, in fact, the largest threat to global stability on the planet. The right-wing version argues that the United States has no obligation to the rest of the world; that the US needs to put “America First,” even when it means ignoring suffering abroad.
These doctrines converge on the idea that the United States needs to stay out of foreign conflicts and even sometimes cross the line into outright apologia for bad actors abroad. This is how Assad and his Russian backers get painted as potential allies against jihadism rather than the human rights abusers they are, both by Gabbard and by Trumpists.
I don’t mean to draw equivalences here. While Gabbard only has a handful of fans on the left, Donald Trump is the president of the United States. But Gabbard’s embrace of anti-Clinton conspiracies and foreign autocrats shows how a strain of left-wing analysis, applied sophomorically, can lead to pretty ugly places. She’s a useful cautionary tale at a time when the left’s stock is rising on the Democratic side of the aisle.