It took me a while to catch up, but was able to listen to this last series of podcasts (still partway through 70) while on long drives the last couple of days. I have to say, I am largely convinced by your reasoning that the Abos did not exist, that "A Story" was authored by VRT, that his claims of Abo life during his time with his mother were attempts by her to conceal the dangers and darkness of life by resort to fanciful tales, among other arguments. Some thoughts that occurred to me:
a) There was some discussion between the two of you whether the Dr. Marsch whom #5 initially meets is VRT or the real Dr. Marsch. My initial thoughts after first reading all 3 novellas is that on the first meeting, it is Dr. Marsch, gathering as much info on the Abos as he can and meeting Aunt Jeannine / Dr. Vail. He certainly seems to have a broader depth of knowledge (such as the unbound simulator information) than Marsch-impersonator VRT would be likely to have. On the second meeting, it is VRT. I think this is the reason #5 can confidently pronounce VRT to be (as they both believe) to be an Abo in the meeting just before the murder of Maitre. He realizes this is not the young man he met on the previous occasion, and presumes, based on the stories he has heard of Abo mimicry, that an Abo has taken his form.
In addition, the true Marsch suggests during their first meeting that #5 is a clone. VRT, in their second meeting, makes the same announcement, as he is unaware that Marsch has earlier made the same pronouncement. It is the last piece of information that convinces #5 that this Marsch is, he believes, an Abo imposter.
b) There is a lot of information from VRT's experiences on St, Croix that seems to be incorporated into "A Story" - I had thought earlier that the bureucratic secret police on St. Croix were Marshmen abos who had mimicked humans, based on the following reflection seen by VRT: "Mme. Duclose’s mirror was behind him, and I could see that his hair was cut short and that he Had a scarred head, as though he had been tortured or had had an operation on his brain or had fought with someone armed with some tearing weapon." I think now it is more likely that the bureaucrats who arrest and imprison him become the Marshmen of his story, which indicates that the date of composition is probably after his arrest, in prison. c) Certainly, the cat in the story reminds me of Poe's "The Black Cat", who bites its owner's hand as well ("One night, returning home, much intoxicated, from one of my haunts about town, I fancied that the cat avoided my presence. I seized him; when, in his fright at my violence, he inflicted a slight wound upon my hand with his teeth. The fury of a demon instantly possessed me. I knew myself no longer."). But the story that seemed to be the greatest influence on "VRT" was Algernon Blackwood's "The Willows" -the eerie tale of two men on a boat trip in a remote area who experience something difficult to describe - but the sense of something unknown and terrifying outside the tent runs through both stories. (And you should definitely review this story on your weird fiction podcast.) d) This was probably discussed sometime over the last year's podcasts, but the likely reason for the belief that the Abos took over the original French settlers is to justify the war against the French - if they are suspected of being aliens, or speaking animals, it justifies the horrors that were committed against them and the seizing of their land and property. This may have been a belief Aunt Jeanine promoted on behalf of the governmental elite, just as Maitre worked for them as an intelligence asset. e) I haven't listened to the section of podcast #70 that discusses religion within the story, but I would agree with the point upon which you touched - the Catholic response to the Nature vs. Nurture dilemma is that both Free Will and Grace are the two God-given gifts that enable us to rise above those two factors, and that in a world where those two gifts are apparently absent, you see the sort of societies that the novellas depict. I think the reason for the frequent references to the monotheistic conception of God in "A Story" is, again for VRT to throw shade on his father's claims about Abo culture, which is that they were polytheistic and believed in "gods". f) Two of the passages that discuss mimicry among the people presumed to be Abos are as follows: (Trenchard, discussing his wife): "But what my son says is true, she was a fine actress. We used to go about performing, she and I. You would not believe the things she could do! She could talk to a man, and he would believe her a girl, a virgin, hardly out of school. But then if she did not like him she would become an old woman—a matter of the voice, you understand, understand, and the muscles of the face, the way she walked and held her hands—(...) “When I married her, Doctor, she was a fine woman. (...). Then she was truly beautiful, magnificent.” (Kisses his fingers, releasing the oar with one hand) “That was not acting. But later when she slept, she could not conceal; every woman is her true age when she sleeps. " (And the military officer discussing Casilla) "“Maitre …” The officer looked up. Cassilla, yawning, stood at his elbow with, a tray, the slave behind her. “Coffee, Maitre,” she said. In the bright daylight he could see fine wrinkles near her eyes; the girl was aging. A pity. He took the cup she proffered, and as she poured, asked how old she was. “Twenty-one, Maitre.” The pot was one of the silver ones with Divisional, decorations, which meant the slave had insisted on it in the kitchen; otherwise they would have given him one of the plain ones from the junior officers’ tables. “You should take better care of yourself.”
On first reading, I had presumed these were clues that the surviving Abo women still maintained some abilities of mimicry and to alter their appearance. But on further reading, this seems like ahead-fake by Wolfe, and it seems to simply reflect that after a night of sex with an abusive, alcoholic, older husband/pimp, or after a night of forced sexual service to two military officers (before beginning a shift serving officers in the mess hall), a prostituted woman or a sex slave is likely to look tired and haggard. Once again, I really enjoy the podcasts!