The evidence just doesn't support your claim that Facebook predominantly censors content from the political right. Facebook produces disproportionately more engagements for right-wing sites[1]. This is reflected in the best performing content on the site -- after the first debate, 9 of the top 10 posts were right leaning [2], which is a regular occurrence.
The existence of popular engagement with a subset of allowed right-wing content does not mean there is no censorship of other right-wing content. If most of the political content on a platform by volume is right-wing, then it actually wouldn't be surprising if most of the censored political content would also be right-wing.
The most engaged with articles on HN are technology-related. That fact does not magically prove that there is also zero moderation of technology-related articles.
>Facebook produces disproportionately more engagements for right-wing sites
Bull.
America is a country where any given election 50% vote Democrat and 50% vote Republican. Look at the chart. Look at the total number of left-wing vs right-wing sites. I bet if you add those up, total left-wing engagements will dwarf the number of total right-wing engagements. Looks to me that engagement is skewed towards left-wing, it's just that there are way more left-wing outfits so individual share is lower. Which makes sense, there is one major right-wing news network, Fox News, there's like 10 that are center-left/left wing which have to share the audience.
[1] https://www.economist.com/graphic-detail/2020/09/10/facebook... [2] https://www.washingtonpost.com/graphics/2020/elections/debat...