The target key was published on 5/20.

    # gpg --list-packets /tmp/snowden.asc
    :pubkey enc packet: version 3, algo 1, keyid 5B50940B79DEBE35
        data: [4096 bits]
    :encrypted data packet:
        length: unknown
        mdc_method: 2
    gpg: encrypted with 4096-bit RSA key, ID 79DEBE35, created 2013-05-20
      "Verax (Informed Democracy Front)"

(79DEBE35 can be found on the subkeys.pgp.net keyserver)