Technically that is not true. When the Cubs got swept in the doubleheader against St. Louis, that also concluded the sweep the last time Cubs was in town.
Bears don't like setting precedence and giving Caleb a no franchise tag commitment would be just that. Caleb had to know that request would fall on deaf ears.
I was not expecting them to compete again for a few years anyways, so I'm glad (yeah, let's go with glad) they picked a direction instead of trying to tread water with their continuinity horsecrap.