Cheney is off the leash and may express his views now that he is no longer part of an administration.
On the subject of keeping criticism to one's self, President Carter, and many others from previous administrations (Republican and Democrat) have not remained silent. The news organizations have a never ending list of previous administration members they call upon to provide contrasting views.
As to the choices in the most recent presidential election, I fault both parties for not putting forth their best.