If you restrict yourself to 2 bad choices, then you can only make bad choices. It doesn't help to label one of them "artificial" and imply the other choice isn't artificial.
It is, in fact, not just crude but actually quite artificial to measure likelihood to interact as a single number, and personalize the list of discussions solely or primarily based on that single number.
Since your chosen crude and artificial indication turned out to be harmful, why double-down on it? Why not seek something better? Off the top of my head, potential avenues of exploration:
• different kinds of interaction are weighted differently. Some could be weighted negatively (e.g. angry reacts)
• [More Like This] / [Fewer Like This] buttons that aren't hidden in the ⋮ menu
• instead of emoji reactions, reactions with explicit editorial meaning, e.g. [Agree] [Heartwearming] [Funny] [Adds to discussion] [Disagree] [Abusive] [Inaccurate] [Doesn't contribute] (this is actually pretty much what Ars Technica's comment system does, but it's an optional second step after up- or down-voting. What if one of these were the only way to up- or down-vote?)
• instead of trying to auto-detect party affiliation, use sentiment analysis to try to detect the tone and toxicity of the conversation. These could be used to adjusts the weights on different kind of interactions, maybe some people share divisive things privately but share pleasant things publicly. (This seems a little paternalistic, but no more so than "artificially" penalizing opposing party affiliation)
• certain kinds of shares could require or encourage editorializing reactions ([Funny] [Thoughtful] [Look at this idiot])
• Facebook conducted surveys that determined that Upworthy-style clickbait sucked, in spite of high engagement, right? Surveys like that could be a regular mechanism to determine weights on interaction types and content classifiers and sentiment analysis. This wouldn't be paternalistic, you wouldn't be deciding for people, they'd be deciding for themselves