Here is a story about the fire that broke out in this building back on January 12, 2010 -
http://www.cbc.ca/news/canada/nova-scotia/story/2010/01/12/ns-fire-south-street.html . The picture (below) is from the story. Another story indicated that the fire had spread to the second story floor joists -
https://groups.google.com/group/hfx.general/browse_thread/thread/ce35c3f792e30221?hl=en.
Based on the story reports, it sounds as though the building would have required a complete rebuild (maybe the bricks could have been saved). Once a historic building is completely rebuilt then it doesn't maintain much of historic significance, it would just be a duplicate of a historic building (in my opinion).
Many old buildings are destroyed by fire because the construction is not up to today's standards. A building like this with multiple units, if built to modern standards, would have kept the fire contained to one unit because of modern fire wall construction that is intented for that purpose.