Might not be the intention but I can see merit in flagging stories with a strong political overtone simply to make the point that this isn't /r/politics -- that that stuff over there.

In fact, if that's the rationale I support it... though it would be good to know what the current rule of thumb is in order to play along.

You need to decide for yourself what crosses the unacceptable content line and what does not. HN only provides the following guideline:

> On-Topic: Anything that good hackers would find interesting. That includes more than hacking and startups. If you had to reduce it to a sentence, the answer might be: anything that gratifies one's intellectual curiosity.

https://news.ycombinator.com/newsguidelines.html