The assumption is that if there's spare GPU power available, the resolution would bump up above 1440p. We'd expect that when performance demands are high, resolution drops below 1440p to hit a stable 30 fps, and when demands are low, resolution would go up above 1440p with that stable 30 fps framerate. Technically though, there's nothing stopping the engine from scaling resolution below 1440p to maintain framerate, but not scaling res up above that and instead scaling framerate up above 30 fps, other than that being a weird choice. But if 1440p was picked for some other reason, it could be the case that some scene can run at 40 fps, 1440p, and are being capped at 30fps, capping framerate. As such, I wouldn't rule that out as nonsensical just yet, even though I can't think of a scenario where that makes sense, but as I don't know how the engine works and what the different bottlenecks are, I'm not in any position to hazard a guess.
Okay, I have hazarded a guess - 1440p is a fixed buffer size. That could be selected for a particular reason to have a static geometry* buffer that can be optimised for its fixed size, and then from that, we can render lower framebuffers but not higher ones. Well, you could upscale, but that could be seen as pointless if the majority of the game is rendering 1440p in very good clarity, why up that fidelity a tiny amount at some points?
* Or anything else in what likely involves complex scene representation.
