It's from the DNF website.
I'd have to speculate, but I imagine what happened was, because of the suit, TT certainly were not going to fund the development, so 3DR had to close, and could not afford to complete the game, completing the game means a considerable influx of cash, so they needed to do whatever it took to get the game completed so it could ship, they can't afford two years of a studio's time, they had no cash, they did however have an almost complete game, the IP of the game and a legal requirement for TT to publish it. So give/sell Gearbox the IP and let them do it, then they can enjoy the cash.
Just a guess though.