Legally, the Governor General makes the appointment, always on the Prime Minister's advice.
From a moral perspective, it comes back to the distinction you make between a legal imperative and a political imperative, as Mr. Moore mentioned. It is useful to recall the difference between these two kinds of political imperatives. A political imperative is the result of promises made by a politician whereas a legal imperative has a much more significant normative force. It deals with constitutional conventions, or constitutional property, which is something else. This is not simply the fear of losing votes, it is a feeling of obligation because of what the Constitution of Canada deems to be obligatory. So, if a convention arises from a practice, it becomes obligatory just as strongly as in the legal sense, though the legal sense has different authority. You have to keep that distinction in mind when you are talking about a moral obligation.
In practice, it means that the current Prime Minister would have a moral obligation to observe his own policy, but that would not mean that the prime minister who succeeded him would have to do the same. Perhaps he would have no moral obligation to do the same thing. If that is the case, he could just not hold consultations, which is quite possible under the bill.