I'm not party to the figures that will have been plugged into the formulas and calculations regarding GG's cost (salary) and benefit (through playing or sale) to the club so, despite me yet to be convinced of GG's advantage for our club, I'm not going to get fussed about why the club has chosen to do what that have.
Alternatively, I could post two variations in anticipation of a smug hindsight follow-up:
Stupid decision - he hasn't improved as a player and we're stuck with him / he's left on a free
Bruce got the best out of him and we eventually sold him for £3.5m - good job he didn't leave on a free.