Once residential plots are occupied in the Sheepfolds you can kiss goodbye to future expansion. From that point of view it makes sense to do something quickly. From a footballing point of view there's no buisness case for expanding. It's at the point the ownership has to decide to stick or twist, probably on behalf of future ownership.
Isn’t the plot for 600 homes on Sheepfolds already sold to a developer? That (and potential issues with light for example) will presumably have been the point when it becomes difficult, not when residents move in.