From that site, about the midseason pushback:
Someone just asked the execs how they decided whether to give "Fringe" or "Dollhouse" the fall launch. Entertainment President Kevin Reilly - I think it was him, anyway - said it was "a high-class problem to have." Whedon had seven scripts written from the get-go, but Abrams finished pilot production sooner. Whdeon welcomed the extra time, the execs said.