We have postal police, DEA and DHS. If I was playing Clue that equals, BurtW using the mail (Postal Police) to send or receive drugs (DEA) internationally (DHS) using Bitcoin for payment.
While your approach seems logical on its face, it fails to explain the U S Marshals service and other agencies. While it is currently unverified, Jean's testimony indicates that no drugs were found, so there vaporizes the DEA nexus.
An alternate possibility is that many agencies simply wanted a cut of the loot and the glory.
There were only two other departments and they are always used as extra bodies and invited as a courtesy to local LEOs.