It pays for itself in 2 weeks now.. before release, but if they sell thousands of them and the 1 TH/s units, the difficulty will go up.. I mean, it'll still pay itself off, but the amount of profit will be different once these are in the wild---IF they get released.
They could produce them (not ship yet) and then use them right after a difficulty adjustments, mine for 2-3 days until the next difficulty jump (a huge one this time) and then start shipping. This would result in a pretty bad slowdown after they switch them off and mail them to the customers (see namecoin problems before merged mining). So I don't think that's a good option.
Should they decide to mine for more than one difficulty-adjustment-period there is another problem: as ArtForz once pointed out (not his words): once your hashrate approaches 50%, you increasingly compete against yourself.
And: them having >50% of hashing power would surely create some pretty bad bitcoin trust-problems that would backfire badly on their profits.
So I think the OP has a point, but I don't think they'll try to exploit it but rather try to make a biz of selling these things.