A thing I thought was interesting re: this, as I was building out my ideas, was that I think Moon sentences should be the broadest and most open for PCs to insert themselves into - a situation that might work for or against them, but one they could easily find themself within.
Because there's a whole other set of sentences you can create for factions and NPCs, and _these_ are the ones that are more clearly oppositional. Now, how you differentiate these is really the trick; I don't know that I have a good way to do it, but one thing I was considering with the bits I wrote was, if I could relate it to the Moon's impulse, it could be a good Moon Sentence. If it was more specifically targeted to a faction's goal, or seemed too difficult to use, I'd move that to an NPC and write something broader for PCs to play with as well.