Why was the BBC story about human trafficking removed?

There was a BBC story [0] about an illegal online slave market enabled by Google, Apple and Instagram; the story was rapidly moving to the top when it was suddenly marked as flagged and removed.

This story passes the HN submission guidelines tests [1]: it is deeply interesting, tied directly to technology, and can provoke interesting discussion about the role of moderation in technology.

In the interest of transparency, why was this story removed, if it was done intentionally? If it was organically flagged, can people who flagged the story explain their motivations for doing so?

[0] https://www.bbc.com/news/technology-50228549

[1] https://news.ycombinator.com/newsguidelines.html