I think you are selling the AHL (and NHL) short in terms of the difference in levels versus NCAA.
While Sanderson is definitely better defensively at the same age, Brannstrom demonstrated arguably more of an impact at the WJC than Sanderson a few years ago, and Brannstrom is much further ahead now that he was then. He's also shown he is almost a PPG player the AHL level over a sustained period of time. Same for Wolanin in the AHL. Now Sanderson still has another year at the WJC, but in terms of comparing the current versions of each player, I think you are really reaching here.
While I have no doubt Sanderson will be much better defensively as a pro rookie than most other rookie D, saying he's already better than Wolanin and Brannstrom is really a stretch. Brannstrom was dominating in the AHL last season and is better now, than then. What you're suggesting is Sanderson would "more than dominate" the AHL right now, which I just don't think is true. I have no doubt he could be an AHL regular now, but all of this comes at a cost of stunting his offensive game. He's a guy we all want to see free wheel it a bit more in the years ahead, and accelerating his path to the NHL won't help there.
Either way, I just don't believe he'd be a better NHL player at this moment than Brannstrom, or probably Wolanin either. I don't want to find out either.