This clearly spam post is at a score of -8 and has been flagged as spam. And yet it has sit there for 12 hours. If nothing else, the 8 downvotes can all flag as spam and it will be deleted. Spam is usually deleted within 15 minutes. Why did this slip through? How can we avoid this happening? Also, if you see this, please so ahead and flag the post as spam.
My guess is that it was just really bad timing (or, well, good timing from the spammer's perspective). It was posted on a what is a Saturday evening or nighttime for people in the Americas and Europe, which comprise the largest segments of our most active users and the mod team, so there were far fewer people online (and that was in turn compounded by the fact that it's Memorial Day weekend in the United States). It happens. Like you said, this was a bit of an outlier, so I'm not concerned going forward. As always, thank you and the other folks who raised flags.