I posted this because it covers the a potential near future where politics repeats itself in a big way which means it's potentially turning into a pattern. That's why I posted this article. Also, to say this situation is "garden-variety politics" is wrong on so many levels in my opinion. Sure, if this was an article talking about the purchase order of jet fighter being delayed, I'd agree with you; This article is talking about a party pushing their representative out of the white house. How is that garden-variety politics?
The other big concern is the type of discussion that is likely in corresponding thread. Are people going to have a conversation of discovery together? or are they just going to bash each other? Each time they bash each other, the health points of this community take a hit, so this is an existential issue for the site. Will HN be a garden of curiosities or a battlefield? It can't be both, and battlefield wins by default and ends in scorched earth. Nothing intellectually interesting about that.
Yes, there are political posts on HN every day that don't get flagged, but that's not because there's carte blanche for politics. It's because some intellectually curious topics have political overlap. The first is the active ingredient; the second is secondary. I wrote about this recently here: https://news.ycombinator.com/item?id=19720659. I wrote a long comment from the opposite angle, defending political articles on HN, here: https://news.ycombinator.com/item?id=17014869.
I grant that the article you submitted also has information that isn't just about current power struggles—it contains historical detail, information about the relationship between the branches of government. But it is too close to the bullseye of partisan conflict for it to fall on the good side of the line for HN.
It's true that all of this is mightily subject to interpretation. But de facto standards have developed over the 12 years that HN has been around, which are not as arbitrary as they at first seem. That's for sure why your submission got flagged. The moderators and the community broadly agree on what those standards are—not by coincidence; it's because the moderators are mostly following the community's lead, while occasionally nudging it in new directions. If you want to see an example of a nudge, https://news.ycombinator.com/item?id=19754780 is a recent one. Note that while that article had political charge, its material wasn't primarily political. That's the kind of thing that's more likely to be on topic here.
p.s. The guidelines say to stick with the original title unless it's misleading or linkbait—important exceptions!