No, I suspect the algorithm takes into account both the sender as well as the content of the message in deciding which comments to push to the front. Reliably 'progressive' senders - especially those which create more 'progressive' engagement - get extra points, this in combination with a 'progressive' message or one critical of any non-'progressive' message seems to be among the deciding factors in what to push to the front. In the absence of 'progressive' senders and/or content the algorithm probably looks for senders who create more engagement over those who don't, adding an extra click barrier between 'progressive' messages and comments which are critical of such.

Popular non-'progressive' senders - Trump and now Musk being the poster child of such - probably get their own comment manager who makes sure there is always some vitriol waiting no matter the message. This does not scale but the Pareto principle makes that it does not have to since there are not that many of such. The same may be true for popular 'progressive' senders where comment managers may make sure there are supportive comments but this seems to be less clear-cut.