If they're aware of it, and doing things this way anyway, probably means they don't see it as a problem, or have decided it could even be beneficial. As long as they don't desperately need the immediate cash to keep their company going, then they'll make more money if people play later anyway, assuming those people buy all DLC that is out at the time they buy the game. (I'm assuming people are more likely to buy DLC if it is already out at the time they do their play-through, seems safe to assume.) This, of course, assumes that the price of the game doesn't go down before then, but that's fully within Obsidian's own control.