I know this quest is severely messed up anyway, but I thought I'd throw in my experience: I had already dealt with the Khans before getting this quest; they were not going to support Caesar. Now I cannot advance this quest, or fix it with the console. What happens now? This is my first playthrough - I waited till the big mid-december patch to start properly. It's not the first bug I've come across in around 50 hours, but it's the first that really messes up the game. In fact, even if a fix was possible, even looking for info about fixing it involves reading so many spoilers it ruins parts of the game anyway.
If anyone has found a way around this, please let me know. I've tried using the console to set the relevant objectives and stages completed, but that didn't work: dialogue with Moore just would not happen then.