I don't think this is about targeting
anyone as a "bad guy", it's about a city recognizing its finite supply of significant buildings.
If there are no laws to govern it, anybody can buy anything and do what they want with it. The difference is that sometimes, especially with certain "heritage buildings", they hold a value over and above the financial cost of the property that is of benefit to our local society, be it a building technique no longer practiced, a link to a historical figure, or just inherent beauty. So in that sense we all have the potential to suffer a loss when one of them is torn down.
As has been said countless times on this forum, this is where the city has to make rules as to what can and can't be done in certain cases. It's not as draconian as it appears - there are rules for everything, be it zoning rules, building codes or what have you. Preserving significant (heritage or not) buildings can be done and usually ends up with an owner or developer who either cares about preserving the building, or at least is willing to work within the rules to do so, while still turning a profit or creating a nice place in which to live/work.
There are no "bad guys", just people trying to accomplish goals that are important to them. It's up to the people who make the rules to ensure that it's done in a manner that protects the city's/citizens' interests as well. Thusfar it appears that Halifax is particularly weak in doing so.