I think it's a pretty good idea myself. E3 is covered mainly by a lot of mainstream sites/Spike TV and honestly, expecting those guys to be covering 2.0 in much depth at all when they'll be pretty much covering Halo 4, Call of Duty: Black Ops 2 and all your usual "Bro" games is pretty much a crapshoot, trailer or no.
August is pretty much the best time to show off the game in it's 2.0 state for a number of reasons. First, Gamescom AND PAX Prime are both happening in August. At the same time, and to me this is the kicker, both of those shows are public events. What better way to show off the game to potential new players by actually putting said game into consumers hands, rather than at the industry standard trade show where most mainstream journalists aren't going to give a shit? Thirdly, PAX and Gamescom may not be covered by mainstream media per se, but it's still going to get a giant spotlight on any gaming website worth it's salt.
Add the Tokyo Game Show for the Japanese playerbase in September and yes, I've no doubt Yoshi-P will keep his word when he means a flood of information. I think he's made a very smart decision here, honestly. Flood everyone with info at those two conventions, and get the extra couple of months to add some extra spitshine. Win-win.