I'll speak for myself and say that the Calgary these people live in is not the reality of what the city actually is today. They have likely been here a long time and have lived in Lake Bonavista for awhile. This is a region of close to 2 Million people, it is not realistic to expect your single-family home community, with homes worth close to 1 million dollars to not evolve to meet the moment of a large metropolitan city. People think of infills as a revolution when in reality it is an evolution. If these people did go through Marda Loop, excusing the construction, they would see a bustling community with a variety of housing that welcomes lots of different people that support a variety local businesses (to spite the construction). What's to fear there? This change has happened to Marda Loop over 30+ years with infills beginning in the 90's/00's-ish?
If the goal is to preserve their individual way of life from the city-wide one step up-zoning (which is all it was) a restriction on your individual property isn't going to affect that. And you're gambling that your neighbours will sign up too. Maybe you do get your neighbours to sign up and your way of life is preserved. But I hope the people interested this restriction understand what they're signing up for, I'm not sure they do. All it takes is one or two neighbours to not go through with it and it was all a waste.
The change to neighbourhoods like Lake Bonavista will happen, granted not as quick as people think, why burden the person buying your home with a label that says this property is worth less because you're limited in who can sell it to?