I think the procurement rules allow for national master standing offers to be put in place for either a competitive process or a non-competitive process. Prior to the issuance of this NMSO for McKinsey, there were others that had been issued to other vendors on a non-competitive basis, and this one was done on a non-competitive basis as well.
I found that Public Services and Procurement Canada's justification was really weak. Then the next step is when departments, agencies or Crowns use it. Each of them should have properly documented why the McKinsey national master standing offer was chosen versus another one where similar services might have been available.