Ok, I just had a sudden realization. I think the guy wasn't being coy, I think he's legit just guessing Spring-Man just like we're guessing newcomers. Why do I say that? Here's the thing. I've had this weird feeling since E3, but... this guys knows stuff, BUT, he very specifically knows video stuff. And even more, he specifically knows about videos that are going to be shown on some kind of big event.
So I'm thinking: Maybe this guy doesn't work for Nintendo at all, but works with some company that do their events and he, somehow, sneaks a peek at the video. That's why he didn't exactly know everything correctly about the E3 direct, everything he said sounded like someone that was watching a video muted.
Ok, now, he posted this on the 4th. EVO was still going strong and there was one day before they would be showing that date teaser. I legit believe he only knows about the date and nothing more. And I'm pretty sure he won't be knowing anything about the actual direct either, since that's not going to have a showing on a big event (maybe at the NY Store...? But I think that's streamed too). Maybe something pops up on 4chan today or tomorrow before the direct, but I'm not betting on it, and I'm not betting he knows Spring-Man either