They quit to protest the firing and using the 20-year old conviction, which was pardoned, as a lame excuse. Why don’t they be honest and just say they quit in solidarity with the fired chief? Maybe they all had some ethics or theft or other issues? Again, maybe this housecleaning is very long overdue and we are likely only getting part of the story.
What difference does it makd that he was pardoned? Pardons are usually the most political action.
Or you are just adding made up things to the story.