It's not fair game. The site guidelines specifically demand that submitters not do this exact thing; instead, you're to use the article's original headline, unless it's misleading or linkbait.

People who submit stories don't own the stories on HN; stories are community property. Being the first to submit a URL does not give someone special privileges to reframe the story for everyone else.

In this case, the reframing that was done was overtly dishonest, implying as it does that The Economist endorses this point of view, which it clearly does not.

I see what you're saying, I was wrong about using the subheading for the title instead of the title.

Your statement that the OP was "overtly dishonest" is ridiculous, come on.