I think you explained it perfectly well. Whether its 2-3-1 or 3-2-1 the idea is that fingering the chord in a different way allows for the index finger to do the hammer-ons. I think you’re right that Taylor is using the 2-3-1 fingering.
To me that seemed odd, and I thought he was using 3-2-1. I’ve tried to learn to use my pinky more. Either way, my point was that any way you put you fingers down, the strings don’t know the difference.
There is a benefit to learning to play any given chord in a number of different ways.