I find it very difficult to believe that the company only upgraded them to terminate them. They are given a standard checkride just like anyone else. Essentially you are given four checkrides (two upgrades) before you are dealt with at the companies discretion. I know the APDs at PSA and they are very fair. If they feel they are given an unfair checkride they have the opportunity to have the checkride observed by a training committee member the second time at their request.
If PSA terminates anyone there is a generally a history of issues. I dont know who was terminated but from my experience it is for way more than just a busted checkride. Its not a right to be given a Captain position .... its earned..just an opinion