I hate NTR, for me cheating is a no-no and rape is a reason to desinstall a game for me, but I don't think the Orion-Nova sex scene was something like that. Yes, Maat forced the situation, but was Nova who wants to do it and Orion have doubts at first but only at first. I think that's why the scene works and why the praetorians don't do a shit, because was consensual.
I can agree that was unnecessary to the Orion-Nova situation, Nova already felt attraction toward Orion but I think that what Caribdis wanted wasn't show or develop that attraction, but show that Nova was more than a timid girl, she was a pervert too, like Orion. Probably Caribdis was scared that the characters of Nova and Luna were to much similar, and making Nova more quirky sexually was his solution.
PD: Sorry if my english is really bad, is not my first (or second) language and usually I don't write a lot, but I really like the game and Nova and I think that the scene was amazing, but yes, can be easily misunderstood.