This is the combination of factors that really appalls me. The smallest amount of research would demonstrate to Abdin or his proponents that their argument is rather improbable.
I can certainly relate to his situation. In 1980, I had found fandom (via "The Motion Picture"), joined the big local Trek club and spent several weeks writing my first ever fanfic. It won second prize in the club's Literary Competition of 1981 and ended up getting illustrated and published in their fanzine (in February 1982). In December 1982, after a longish hiatus, a Pocket Books' original Trek novel, "Black Fire" by Sonni Cooper, was released. Yes, the one where Spock becomes a renegade pirate.
A former work colleague, who was back in the USA by then, bought me a copy in San Francisco and sent it by airmail, so I had it at least three months before any other local fans. (The bookshops here used to sea freight their books in those days.)
To my bewilderment, the more-sedate, ship-based subplot of "Black Fire"
paralleled my short story in at least 13 ways, right down to exploding bridge consoles in the "teaser" and a new, temporary First Officer of the USS Enterprise called Thorin. (My character was an Andorian, Therin; his fanfic debut.) As a newbie fan, so excited to own and read the latest licensed novel, it was crazy to find so many touchstones to my own story. I reasoned that there was no way that Sonni Cooper had access to my fanfic, nor would she need/want to. My story was still in longhand as she was typing her manuscript. Indeed, probably her book was
already submitted and undergoing editing before I even started writing mine.
I wrote it off as a series of coincidental, random choices. Or, both of us tapping into the Cosmic Consciousness. It was certainly proof to me that the unlikely can happen. I bet if the Internet was around in 1982, I'd have been more suspicious.