I think "probably off-topic" is different from strictly "off-topic". I do remember that from the guidelines, though also from the guidelines:

> 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.

I think seeing historically uncommon/rare events unfold also falls under gratifying one's intellectual curiosity (though I admit this might be a stretch in this particular story). Additionally, there are multiple stories that pop up (once or twice per day, from my anecdotal experience) that are also stories that'd be covered on TV news.