BS”D
PM:
I didn’t say he says its Muttar, all I said is that he is Mechalek between turning off the gas and actual Kiboyi (OC Chelek 1, forget actual Simin).
He does not say (in print, I have not heard him in person say otherwise) it is Muttar to turn off the gas.
Besides, Rav Moshe says (If memory serves) (I think in the Chelek Daled Teshuva) that Gas is considered to be “far away” & removed from the fire. Each “particle” of gas may (once again, its not my svorah, and I’m only giving my understanding, not Rav Moshe’s and I may be incorrect) be considered seperate, as its in the pipes, not even directed towards the flame in question; so its different than all of the other cases brought, where the source is already “attached” to the flame.
I don’t think anyone would suggest you should turn off or lower a flame not for Ochel Nefesh purposes on Yom Tov. But if your Rav does allow it, who am I to argue?