So I read the post, and then briefly looked at the rest of the links. The comet is still being affected by gravity, causing its path, but it was mostly affected by cometary outgassing.
You haven't done your homework.
https://arxiv.org/pdf/1810.11490.pdfFrom a theoretical point of view, Rafikov (2018) has shown that if outgassing was responsible for the acceleration (as originally proposed by Micheli et al. 2018), then the associated outgassing torques would have driven a rapid evolution in ‘Oumuamua’s spin, incompatible with observations.
https://blogs.scientificamerican.com/observations/6-strange-facts-about-the-interstellar-visitor-oumuamua/The extra push for ‘Oumuamua could have originated by cometary outgassing if at least a tenth of its mass evaporated. But such massive evaporation would have naturally led to the appearance of a cometary tail, and none was seen. The Spitzer telescope observations also place tight limits on any carbon-based molecules or dust around ‘Oumuamua and rule out the possibility that normal cometary outgassing is at play (unless it is composed of pure water). Moreover, cometary outgassing would have changed the rotation period of ‘Oumuamua, and no such change was observed.
https://academic.oup.com/mnras/article/476/3/3031/4909830The lack of evidence for outgassing means that the purely observational prior favours an asteroid-like composition.
https://arxiv.org/pdf/1809.06389.pdfHowever, a recent measurement by Micheli et al (2018) of a substantial non-gravitational acceleration affecting the orbit of this object has been interpreted as resulting from its cometary activity, which must be rather
vigorous. Here we critically re-assess this interpretation by exploring the implications of measured
non-gravitational acceleration for the ’Oumuamua’s rotational state. We show that outgassing torques
should drive rapid evolution of ’Oumuamua’s spin (on a timescale of a few days), assuming torque
asymmetry typical for the Solar System comets. However, given the highly elongated shape of the
object, its torque asymmetry is likely higher, implying even faster evolution. This would have resulted
in rapid rotational fission of ’Oumuamua during its journey through the Solar System and is clearly
incompatible with the relative stability of its rotational state inferred from photometric variability.
Based on these arguments, as well as the lack of direct signs of outgassing, we conclude that the
classification of ’Oumuamua as a comet (invoked to explain its claimed anomalous acceleration) is
questionable.