alt Hacker NewsPosts that break guidelines should be flagged, and the bar should be pretty high.
I don't think there is a guideline that bans posts from "pushing an agenda" (which would be very subjective)
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I draw a distinction between posts and comments here.
Comments that are "pushing an agenda" are noticeable because they Just. Will. Not. Deviate. From. The. Party. Line. Ever. They will never acknowledge an opposing viewpoint's point, no matter how valid. It's not a good faith conversation, and it deserves to be both downvoted and flagged. When one side (or both!) is like talking to a brick wall, this is often what's going on.
Posts are harder. If user X posts articles pushing a viewpoint, that's harder to prove that they're intending to do that. Or it would be, except that user X will also usually be active in the discussion about the article, and their comments will fit the above pattern. If you see that, then you can say that the post was probably pushing an agenda as well.
From https://news.ycombinator.com/newsguidelines.html: "Please don't use Hacker News for political or ideological battle. It tramples curiosity."
"Agendas" are often ideological battlegrounds. I flag comments, even those I agree with, that I recognize from experience are going to lead to the same tired, off-topic debates and flame wars.
Lately, I've also been maintaining a personal uBlock Origin filter list to hide certain prolific rule breakers. I would love if HN had an equivalent built-in "killfile"[0] functionality for auto-hiding submissions and comments. (This has been suggested to the admins, and was seemingly received favorably, but I'm sure it's a matter of resources.)
[0]: https://en.wikipedia.org/wiki/Kill_file