My main thought was that a text companion to an audio story would be different than an standalone fic, probably more like a script than a short story. If you were writing to maximize the possibilities of the new medium, that is. So that in itself would help to reinforce the primacy of the audio version.

But I have no issue with idea of making text available in a .txt or .rtf format, with the possible exception that I wonder about long-term archiving potential. (Would the file be available on a Rapidshare/Megaupload type service? What if the download expired? Would it eventually be archived in its standard form on the AO3 or a similar site?)