I would agree. Perdiccas might have fit the role had he given up his ambitions while regent. He could have chosen to simply keep the peace and hold the empire together until Alexander IV came of age. However instead he decided to make a play for power himself by divorcing Antipater's daughter Nicaea and trying to marry Alexander's sister Cleopatra. If Perdiccas had of stayed married to Antipater's daughter and recognized Ptolemy's rule in Egypt the outcome would have been better. As far as I know Antipater and Ptolemy were always loyal to the dynasty and Alexander IV.Except it didn't? The parts he conquered held together fine, under the various generals. Had there been one general who defeated the others, he'd have held the whole territory much as Alexander (or the Persian predecessors did)
Other options are Antigonus crushes everyone or Seleucus avoids assassination, taking Macedon, and leaving only Egypt independent.