I'm sorry but... yeah, I'm not buying this. There's a number of holes here I think.
1. There's no logical sense to the Triforce not being a major aspect of the plot. It doesn't match up with a number of things. Sure there are plenty of games in the series that do not feature the Triforce, but nearly every main title did, and certainly they would not exclude mentioning such an important aspect of the series' lore in the one game that's supposed to establish that lore. It also doesn't match up with the already present attention on the Triforce, or perhaps lack thereof. We've seen the Triforce absent on symbols that normally have it (like the Royal Family's crest), and while one would think "Oh hey, if it's absent then that means it won't appear, right?" but at this point we're nearly 100% certain that this game will show the forming or at least the history of the Royal Family, which means with certainty that we will find out when and why they added the Triforce to the crest.
2. The big dome-like cloud. It's wayyyy too much of a coincidence that the one thing that relates to the Triforce is something that we've already seen, that's one of the most mysterious things in all of our current Skyward Sword information, and has been theorized about recently.
3. Doesn't this scream Triforce Hunt to you a little? When other time has the Triforce existed as anything vaguely close to an optional collectible? And going with series lore, why the hell would it be? Therefore, this is already based on an existing (and proven false) rumor from another game, which would be Ocarina of Time with its whole Triforce Hunt mess.
4. There's absolutely no way that they'd let this slip. It's not even possible. Nintendo is always tight-lipped about Zelda's story, and this would be a major revelation in a number of ways. Sure, this could be a single employee who broke the rules or something, but considering that's never happened with Zelda and the fact that he'd be fired so fast and he'd know it... it's just highly improbable.
5. If he's not supposed to not give out too much info, why did he just reveal the role of the single most important object in the entirety of the Zelda universe?
Be interesting if it turns out to be true, although highly unusual and unfortunate for Nintendo. I also would not like it that much since it would ruin the direction that the plot of Skyward Sword has been (strongly) implied to be taking, and it was a good direction that was promising to be incredibly interesting. That and the fact that it would tarnish the significance of the Triforce to make it into some kind of optional collectible for 100% completion... it's just a bad idea no matter how you look at it.