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Again, the point is that the existence of biological systems, mechanisms, behaviors, etc is not evidence of 'compatibility' with evolution without engaging in logical fallacy.

This would be true in a fully observable environment where all mechanisms are observable and parameters are measurable, and everything adds up to a rule. In a post-Newtonian world this approach is not sufficient anymore. When you have unobservable mechanism or the observation itself changes the outcome, you instead now observe input states and output states and design a postulative framework that can bridge the two states. Then you test the framework by throwing scenarios and supplemental observations at it. In other words, you try to break it by finding inconsistent states and incompatible behaviour.

Simple example: for centuries we thought the sun was made of coal until we realized that it would burn out too fast. Then we tried to explain it with fission but spectral analysis did not provide evidence of fissable materials and the energy balance didn't add up. When Bethe and Weizsaecker provided their CNO cycle explanation it was a theory at the time and fusion was little more than a concept. Over the decades we attempted to disprove each step in the CNO cycle to no avail and by now B/W is the accepted standard for solar energy production. But for all we know it could also be Superman's hampster on a warp drive bike providing energy in the core.

For a more recent and abstract example, QED and QCD are complex frameworks that involve the concept of exchanging a virtual particle in order to describe weak & strong interactions. We can observe certain input and output parameters but we have no direct observation of said particle. I would argue that the QED is one of the most scrutinized conceptual frameworks in physics and that it has held up remarkably well. However, each experiment, each interpretation of observations was founded in the assumption of a QED.

If you postulate evolution as a conceptual framework with a few practical drivers such as a gradient towards better adaptability, you can test observable parameters against it without commiting a fallacy (provided of course appropriate bracketing on the part of the researcher). As with CNO or QED, individual observations will not prove or disprove the theory, but they provide waypoints. If we agree that sexual reproduction offers greater adaptability than asexual there should be a gradient from A to S.

If we found only members of A and members of S, it would be hard to postulate that there is a gradient towards S for organisms of higher complexity. While it would also not conclusively prove that some imaginary being decided to make some A's and some S's and this will stay like this for all eternity, I would consider it evidence. However, the discovery of the same species in A and S states, parthenogenesis, hermaphrodism and so forth all are (IMHO) pointers towards a dynamic system. (Parthenogenesis (IMHO again) is a remnant of an A-centric ancestry which tries to compensate for the shortfalls of S - but that's another discussion).

Main point is that postulating the existence of a conceptual framework with unobservable mechanisms, and using observations of observable members of the corresponding system to test the compatibiity with such framework does not constitute logical fallacy.