If the issue had been leaked direct to the Herald or Fairfax (as if the usual journo’s there would have the geeky competence to investigate as Keith did), the original source might never have been released short of a totally open Ministerial or MSD press release.

I don't know if that's true; in fact, I think it would have played out the same way. Say it had been a Fairfax journalist who broke the original story - why would Claire hold back from investigating her tip-off about Ira? If leaking his name was a ploy by MSD/Bennett staffers to distract attention from the main issue, that motivation would still exist regardless of who first published the story.