She left for the same reason Sarah left salomon, to have a better/more safe part in the company ( im assuming, since thats what was written in the article). You can't be a pro skier all your life, and well it just doesn't pay that well.
Head has some pretty shit womans skis right now.......and the market is on a stead growing rate. Head sees that as an opportunity to make some cash, but they need someone who knows the market. The ARW is argueably the best woman's park ski out there, so having Grete on the team just makes common sence. Armada is awsome, but being awsome just doesn't pay the bills like the big boys can.