The problem, in its most general form, is this. But as parents, we do play favorites. Parental love is partial through and through. Therefore, it would seem, one or the other of these conceptions has to be modified or abandoned. Nonetheless, we parents do play favorites.
Parental love is completely partial.
We think this is morally acceptable. In fact, we think there is something objectionable about the parent who is not partial toward his own children. Therefore, it seems one of these conceptions must be modified or rejected. This revised version is still plagiarism. Of course if the student had given a citation, explaining that she was merely paraphrasing the author, then that would not be plagiarism.