I recall some time after JL's theatrical release when those and many other shots and scenes were leaked, that some of the VFX people working on those scenes said they were told to finish them out. I can't remember if it was a contractual obligation, or what.
It's been over two years, none of us here right now really have an idea of what's done and what isn't. It's entirely possible Zack was able to get a crew together to donate time (unlikely, but very possible) to finish some things out. Or, as I mentioned in the first sentence, some additional VFX work was still being done (for whatever reason) even after the movie released.
People will continue to debate despite what Zack and Jay Oliva (and even some other cast and crew who have spoken out over the last two years) say. Despite them being the ones who worked on the actual movie… And when evidence begins to mount suggesting the movie is far, far closer than most (or even just the detractors believe), they move to the next steps of either a) calling Zack a liar, or b) saying that it will still cost $40 million to finish out what's left.
Edit: Good conversations so far, by the way. Let's keep it this way.