I agree those are mere plausible ideas with no real foundations, but the aim is to open our imagination to the realm of the plausible. Even those phenomena that are improbable and barely plausible, there are some of them we will encounter, and thanks to the work of sf writers we will not be too much caught off guard.

Specifically for your point on entropy and stability of vortices, I don't disagree totally though I'd like to call your attention on what is known with magnetic skyrmions. They are stable because to change spin the particles would need to overcome huge energy barriers. Then, the only difference with fluid vortices is that in a fluid there is friction that can bring the fluid elements to gradually shed their angular momentum at the contact of other elements with a different momentum. But in superfluid states that you could encounter at very low temperatures (like on some distant planet etc), it is plausible that there would exist analogous energy barriers preventing the fluid elements to directly shed their momentum! And even though, you can of course imagine fluidic circuits and rotational computations, which would have some stability thanks to the superfluid state.

Of course all of that is baseless speculation, but the point of SF is precisely to appreciate the vastness of the world of plausible phenomena...