Actually, if you look at that cutscene in context, it comes up immediately after Sora disobeys orders from Mickey and goes to fight Demyx. The scene with Xemnas happens, then Sora fights Demyx.
Nobody feed this troll please.
You're argument is valid yet again. But the way that it's worded in the Xehanort reports, "Keyblade Masters have the abilities to transfer their hearts" sounds like it's a universal truth, as if he had learned it.
Besides, being immersed in darkness wouldn't teach him it. If he actually learned it on his own, he would have had to test it, and I doubt he would have taken such an old body.
It is speculation, but it's supported by little facts here and there.
He did test it. He tried it with Ven; he nearly killed him.