There is another possibility of what might have happened here. It's only based on a gut feeling of mine rather than much factual evidence but it would make for a plausible explanation. I have recently watched the 30 year reunion of the UFC 1 fighters and noticed that to this very day, Ken Shamrock is still trying to gaslight people into believing Royce Gracie used his Gi to strangle him.
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Of course, in the actual video of the fight, it is not visible what exactly happens, but we DO have definitive proof of it not being any type of Gi strangle but a basic RNC.
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Now, what i suspect happened is that Jason DeLucia, who has friendly ties to both the Gracies and the Shamrock camp, was told by Shamrock that Royce applied a Gi choke. If that actually happened, the DeLucia / Jenkins finish would in fact be the first RNC in UFC history.
So if Shamrock KEEPS insisting on it being a Gi choke at every opportunity he gets even 30 years after the fact (which makes sense for him, since his excuse for losing has always been that he wasn't allowed to wear shoes because they were considered weapons, but Gracie was allowed to use his Gi as a weapon), it's quite possible that Jason either believes Shamrock (despite Gracie having stated at every opportunity that it was a RNC) or at the very least stays willfully ignorant of it being an RNC because that gives his choke against Jenkins historical relevance as the first RNC in UFC history.
Long story short, it is very possible that the DeLucia / Jenkins match happened right before the finals as established, but he doesn't count the Shamrock / Gracie match, which was the only other RNC pre-finals.
EDIT: I HAVE THE SOLUTION! I can confirm that the Jason DeLucia vs. Trent Jenkins match took place immediately before the main event. Stupid me didn't listen to the actual podcast with Jason before i posted it. He is asked about when the fight took place and this is what basically happened: The alternates were not supposed to fight at UFC 1. The problem was that all the fights were much shorter than Rorion Gracie expected, so the decision for the DeLucia / Jenkins fight to happen was made during the actual event. So the fight happened right before the Gracie vs. Gordeau fight, confirming my suspicion that DeLucia's claim about doing the first RNC in UFC history is bullshit and doesn't take Gracie / Shamrock into account.
Finally, we solved the mystery.
