I think Jobs was one of those exceedingly rare individuals that could gracefully handle either situation. He was just as dangerous as a startup founder as he was the CEO of a huge corporation.
Forstall apparently was one of Jobs' key players, despite having a huge target on his back where other Apple managers were concerned. I bet that Jobs knew exactly what Forstall's strengths and weaknesses were, and he managed to use Forstall for his strengths while keeping his weaknesses contained. With Jobs' passing, Forstall lost his protection, and Apple lost the person that was effectively able to manage someone like Forstall.