It's the incitement that we should be concerned about, and balancing restrictions with peaceful freedom of expression.
not to mention one of the instigators of this entire thing has been the president of the united states. his actions have consequences that are 100x order of magnitude than your rioter on the street.
Could you please ban these topics then ? After all, this thread is a political discussion and imbalanced or biased statements naturally invite responses to correct them.
The bottom line is that a certain amount of political discussion is inevitable here, and users (all of us, on all sides) need to learn the skills of doing that while remaining within the site rules: https://news.ycombinator.com/newsguidelines.html. That's definitely doable, as many HN commenters demonstrate every day.