I think he's dicounting the massive power discrepency there since DDD kills zelda so much easier.
Honestly, I don't see why this matters much when it comes to D3. Zelda being light works both ways - she dies earlier (DDD grins), but now DDD can't chaingrab her. (DDD frowns)
I think those two factors alone cancel out the weight issues here. Oh, but no matter how you slice it, Zelda's hitting him with the most powerful aerials in the game. It's a chore to fight him on some stages in my opinion, but other than that, this fight isn't as bad as I originally thought it was. WiFi Zelda vs. DDD is definitely in his favor... but offline, it's a fun fight, for me.
And really, outside of DDD having the ability to kill Zelda earlier, what's keeping this from being, at the very least, 65:35? His aerials can be a bit of a pain at lower %s, but come on, you can consistently sweetspot him on his bair, and you're always getting the better deal. I don't care if 13% to Zelda means just about as much as 20% means to DDD; a sweetspotted kick is not a fair trade when superarmored attacks are not taken into consideration. His aerials don't even consistently kill Zelda. I have not done any testing for exact numbers, but I am sure that DDD's fresh aerials do not kill Zelda sooner than Zelda's kill him. He moves slow as hell in the air, he's a big target, he gets edgeguarded dirtily, he can't even outcamp friggin Din's, he can't consistently WoP Zelda, and he doesn't even hamper her approaches all that well. His grab and throws are still good, and he still has his killing power. I take his killing power into consideration not because it works oh-so-well against someone light like Zelda, but instead because he has comparable killing %s to Zelda... that is, when they're on the ground. If anything, they should be killing each other at around the same %s.
Also... once again, DDD cannot chaingrab Zelda, whereas Zelda can still dtilt lock DDD. There goes a ton of his stock right there. (Also, I say he's dying at 125% instead of 150% on average; dtilt -> Dsmash and then edgeguard, or just LK earlier. Might be 150% for at least one stock, though.)