It is a correct use of the word. It is not a shorthand for "organization". This is from the Reader's Digest Great Encyclopedic Dictionary (copr. 1966, 2nd ed. 1967) (pre-internet. this is relevant)
4) An instrument of agency of communication: especially a newspaper or periodical published in the interest of a political party, religious denomination, etc.
I would think it obvious that this is Mr. Hume's frame of reference. He makes his living with words, therefore he will tend to be precise in his speech.