Agree, E3 doesn't make sense for Rockstar. Why would they be part of a week of big gaming news? That's not how Rockstar rolls.
E3 would be weird for them, no? Not just cause of the usual Rockstar don't go to E3, but it's a fairly poor way to get meaty information out about your game, it's mostly just trailers and gameplay videos to everyone who doesn't attend. Even if true, I think we'll hear something before then.
That's simply not true. Since 2001 Rockstar has had plenty of appearances at E3 from exclusive trailers and gameplay reveals to booths and buses set up on the show floor. The only thing that has really changed is that Rockstar's output has dwindled to a single title and unless they've got a partnership with one of the big 3, IE Sony and the GTAV bundle, there's little point to show up.
But let's nip this whole "Rockstar don't do E3" thing as its factually false.
A key reason they go with GI (they did it with IGN for GTA:O too if I recall) is most likely because it's still one of the vest best ways to get A LOT of information out about your game. Characters, their motivations, the world, the locations what you can do, all that types of stuff. E3 is dominated by cut-heavy trailers and vertical slice gameplay demos. They either give very vague information about what you can do and what you're going to see, or give you a very condensed and directed view of what you can do, which is something Rockstar never really does, not publicly anyway.
We're reading a lot out of an email from a guy who may or may not have a tiny role in the game, but if we're to assume he is implying the big blow out is at E3 then that would be a very, very new thing for Rockstar. But a new trailer or a wee bit of information? Perfectly possible of course.