If Trump decides to go pull the plug on invading Greenland an uses the 11th Airborne, McBride would, I would assume, at a minimum, be relieved of his duties with the 11th Airborne and sent back to Canada, with either a subordinate ops staff officer or the Deputy Commanding General (Support) or some combination filling in for the duties of the Deputy Commanding General (Operations).

Depending on the details of timing of the operation and the US-Canada diplomatic situation as a result, what happens after he is relieved might not be as simple as a return to Canada, he might conceivably even end up as a POW.