This is an interview with the astronomer Karen Meech discussing the reasons why she doesn’t think Aumuamua is of alien origin. It seems the nut of the question, besides the inexplicable acceleration, is the shape of the object. She presents an image of a light reading taken that seems to indicate a cigar shaped geometry, not a flat one. This runs counter to the above linked articles claim that it’s 91% certainly flat.
One thing that jumped out to me. She used a term, I don’t have time to pinpoint it at the moment, where she says something to the effect that the notion of it being flat is “impossible” or something. Essentially saying because such a shape would be so out of the realm of what is considered possible that it shouldn’t be considered. This strikes me as an unjustified assumption, the entire point is that the thing doesn’t look or act like any other object we have seen.