DC probably had him under contract so he figured he might as well use him. We now have to live with that mistake for eternity.
Do you think he was? I wouldn't have thought so, but I don't understand all the specifics. So the main characters were paid whether they were on or not? And then, what would be the purpose of keeping the daily cast at 6 or under?
In one interview (I think it was DS Special Edition) DC is laughing about how often he would bring back an actor that he liked. Roger Davis was the example he used. My guess is that Roger was quite the ass kisser.