If the development rules were followed, the bmo building would still sit on this site:
“Demolition is the complete removal of a structure from a site including removal of any foundations, footings, piles or slabs to a minimum 0.5m below grade. A Development Permit and a Building Permit are required to demolish a building.”
they are lots of legally available options under which what was proposed could be implemented and enforced even if they were development and/or building permit related. both of those are often conditioned and need to be in place prior to the city issuing a demolition permit if there is a concern that conditioning the demolition permit might be problematic.