How that announcement couldn't scare people more than a tad, I've not a clue.
First, 1 million box sales, if that was what we were talking about here (we're not, but more on that in a moment) in a month really wouldn't be that impressive for a heavily advertised multi-platform AAA game. It wouldn't be terrible, of course, but hardly impressive in a world were GW2 (also b2P, not multi-platform, and not nearly as advertised) claimed 2 million box sales in two weeks (granted, given pre-sales and wording they gamed that more than a tad, but still...).
Second, if they had sold 1 million boxes, they would have said so. They didn't, they said 'registrations'. One does not have to have bought the game to register. One doesn't have to have played the game to register. Hell, one doesn't even have to have had much interest in the game to register. People, likely a whole lot of people, registered to enter the codes and then, for various reasons, never bought the game. Others registered to ask pre-sale questions (there's been numerous such threads) or just troll the boards.
The relationship between "registrations" and actual sales is tenuous at best. Trion clearly wants people to assume that registrations = boxes sold -- and it's telling that they pulled this
exact same stunt with Rift -- but that's clearly not the case.
If they'd made 1 million sales, they would have bragged about that instead of "registrations". That fact that they can't even brag about having sold a million boxes, something that wouldn't even be particularly impressive under the circumstances, should be very worrisome to anyone concerned about the long term health of this game.