PM- thanks for your erudition and your exhasutive research. MAZEL TOV again on the birth of your child!
To the matter at hand. i have the gemoro in front of me and, although you are of course right in what you wrote ( I was unsure as i ahd forgotten the sugya) look into the tosofos D’H “Umistapek” !!! Tosefos writes CLEARLY that it is GRAM KIBUI !!! Toseof gice another rason why taking oil(fuel0 out of a candle is ossur. So- we are back at the begnning that it can indeed be gram kibui.
I do not have your erudition (and your library) and i thank you for your indication of all those Poskim, but the question remains : why isn’t it gram kibui? Toseofs seems to have accepted this.
Kibui would generally mean a direct dousing of the flame,not withholding fuel.
Look, I realize that you have all these sources but the question remains: why???