I doubt if the NDP would ever appoint Senators. Unless they appointed almost half the Senate in one swoop it would only legitimize the Senate opposition to the NDP. I cannot think of a scenario where the NDP would be pushed off its policy for short term political gains.
For Wallin and Duffy, I do feel somewhat sorry about their lack of due process. Of course then I remember how they were the Conservative attack dogs and them gleefully filling the role and the feeling goes away.