And why (after 4 years and counting) have they not done so anywhere at all?
It took roughly that long for Bittorrent protocol to get barred in many a Western country, and you would think that the inclination and motivation to stop a money service would be much more vociferous than just a file transfer network.
Then bitcoin traffic would be concealed within unrestricted traffic. Bitcoin transactions are small. Blockchain changes could be broadcast on ham radio.