The RCMP response to the AR15 being restricted is because it's part of the M16 family rifle which is restricted. It's not answering any questions, it's just it's restricted because it's restricted.
One of the reason could be because the upper is interchangeable easily. Which means it's the upper that should be restricted or non-restricted with it's own serial number for example.
Making the AR15 compliant to non-restricted would be very easy. But we all know the truth is, it's an organization that wants monopoly on force, the end. There is absolutely no logic behind gun control except control and monopoly on force. The Armalite platform is used by the RCMP and the Canadian forces. Let them have it, I don't care, we have our Tavors and upcoming X95s which are better anyway.