You are right. I do not agree with Professor Pelletier.
The reason I don't agree is that the British Parliament has legislated on prorogation, and my reading of that legislation--I've read the text of the three acts--is that it says nothing about the powers of the crown. It simply says prorogation shall not occur.
Now, what we could do in Canada is not legislate on prorogation but on the Prime Minister's right to advise the crown, his powers to advise the crown. I suggest in my paper that that's a safe way to go, but my reading of British precedent is that the British Parliament has never been in any doubt about its power to regulate the use of prorogation through legislation. It has never had any doubt. It had that power in 1867, it had it in 1918, and doubtless it believes it still has it.