I got my GCMS notes finally last month. They did not provide any further explanation. It just said this:
I have reviewed the application. I have considered the following factors in my decision. The purpose of the applicant's visit to Canada is not consistent with a temporary stay given the details provided in the application. Weighing the factors in this application. I am not satisfied that the applicant will depart Canada at the end of the period authorized for their stay. For the reasons above, I have refused this application.