I think a lot of this makes sense. The only thing I'd push back about jr worlds at 50 kg is that argument also applies to DT's much worse result too. Also, a bunch of future world champs started at 50 kg JRs.
But I agree that freestyle isn't that relevant, just one piece of evidence of several. To me, when I think about the match, I think Spencer is a particularly bad match up for that DT. He was extremely technical, but didn't have a ton of horsepower before he grew into his body. Hard to imagine now lol, but when he bumped from 112 to 135, he got caught a couple times by stronger wrestlers. You saw that same dynamic again when he bumped to 157 until he got stronger. Even that second year at 157, there were moments when he struggled to finish shots and got caught underneath if he didn't get to the ankle (DSJ and Bubba).
His overall ability still made him dominant, but Spencer not only has a similar technical prowess, he's also by all accounts freakishly powerful. I think that's the difference in the match.