Teaching and advocating
"Teach about" is not the same as "advocate." For people who get so hot over "nuance," you seem to have a lot of trouble with it.
To simplify, the history of the Soviet Union can be taught in schools, including the gulags, and a non-war death toll of its own citizens unmatched by any other tyranny in human history.
Or you can have a teacher who ignores this and just tells his students how great Castro's Cuba is, and that they have free medical care and a wonderfully high literacy rate.
I've seen both of these, and a lot in between.