Consider the following dialogue from the episode itself, involving the EMH, the publisher, Janeway, and Admiral Paris:
ADMIRAL PARIS [on screen]: I had the dubious privilege of playing a new holonovel apparently written by your EMH. I'm surprised that you would allow the Doctor to discredit your crew like this.
JANEWAY: He's still making revisions. The programme shouldn't have been distributed yet.
ADMIRAL PARIS [on screen]: Well, it has been. Mister Barclay tells me it's already being played in thousands of holosuites.
EMH: You assured me you were going to wait for my revisions. I demand that you recall every copy and issue a public apology to Captain Janeway and her crew.
BROHT [on screen]: I won't do anything of the sort.
JANEWAY: I don't see that you have a choice, Mister Broht. Authors have rights.
BROHT [on screen]: Not in this case.
EMH: What do you mean?
BROHT [on screen]: The Doctor is a hologram.
BROHT [on screen]: According to Federation law, holograms have no rights.
I believe it is clear from this dialogue that the publisher (Broht) saw an opportunity — he had accurately predicted the popularity of the holonovel — and simply refused to wait for the EMH to finish his many revisions.
Knowing that the EMH would have continued delaying in order to accommodate revisions, Broht went ahead and published the holonovel on his own, under the premise that the EMH has no rights and therefore has no say in the fate of the holonovel.
It may have crossed Broht's mind that Zimmerman may have rights regarding the holonovel (as a creation by proxy), but Broht had already taken the action of publishing and distributing the holonovel and therefore needed to come up with a fairly solid reason for why he felt he had the privilege to do so.