Clickbait title. It's just one case where the cops use the fact that suspects used signal to make the justice think that they could be terrorist.

If you find a torrent with the exact same files, yes you can seed without downloading first. What I do it's to start the new torrent so it create the files. Pause the torrent. Overwrite the created files with the files I already have. Then verify the torrent. And finally resume it to seed.