>>42472627
I never found it unsettling because it didn't seem to me like he did. We were joking earlier about her offscreening her own food, but Twilight did more than that. She was gathering a lot of boiled water (impossibly finding tons of firewood in the dunes, I guess), scouting the area for food and danger, etc. She looked like she was preparing to go back to Equestria, despite it being clear that she didn't have all the pieces yet, and not because she was expecting to get the rest of them from Thorax.
Besides Thorax's perspective never exposing an inkling of a thought to slow her down, he also doesn't have total control over her. Pharynx's investigation prevents him from even having leverage over her food supply (this falls apart from both sides, of course, and Twilight doesn't even know that), but Twilight can also put a hole him him if he ever turns from a friend into a threat.

If >>42472592 was about Thorax having no malice, the core of this post is that even though Twilight needs him to live, she doesn't act like it. So I just don't see it from either direction.