And whatever your definition of the goal, the advisor was clearly implying that if she couldn't turn in excellent work, she'd have to do something dishonest, and that's just not so.
The definition of the goal is important here. If the goal is to turn in excellent work and someone is incapable of doing that for whatever reason, then they would have to either do something dishonest or not accomplish the goal. The moral path would certainly be to not accomplish the goal.
I'm pretty sure we agree on the fundamental issue here. That is, that plagiarism is unacceptable regardless of the situation. I agree that, as you said, "You never have to plagiarize.", but I don't think that's what the advisor meant and neither did I.
In any case, I realize that I'm splitting hairs and this isn't a very important issue.