Given what has been open sourced so far, it makes sense that content that is likely to be controversial, or content that generates neutral to negative engagement would have a smaller probability of being displayed.

I suspected this and told my far-right/left wing acquaintances, that no, Twitter (and Facebook too) isn't suppressing you, your content is just a net-negative from the platform's perspective. The platform is in the business of keeping the bulk of its users and advertisers happy.