My understanding is it's up to each individual homeowner to add the RC to his/her title. I suspect there will be a lot of pressure from neighbours to conform.
A few communities are in the process of registering a blanket restrictive covenant to preserve their single family only status. Roxboro and Rideau are doing it and I'm sure there will be others. The appeals lawyers are going to get very rich.
RNDSQR was on the brink of bankruptcy and had to exit the majority of their projects, including this one. This was likely the main reason for the extended delay. Eagle Crest is the current developer of this project -
https://www.eaglecrestconstruction.ca/projects/flyover
I think that goes without saying. My point is there's precedent now, so I wouldn't depend on having a RC as a back-up plan, if the blanket rezoning is approved.