an oppportune moment to sneak out the decision

Given that there's 5 fraccing relating determinations being clearly held back (none of the non-fraccing determinations have been delayed anything like as long). It's a reasonable guess it's the political sensitivity that's behind the delay.

If that's the case then right now while the media is obsessed with leadership spills would be a good time to slip it out and ensure the story gets no airplay.

just a theory.