Of course. But if the land/labor/materials have gone so high in price, it is possible that even with zero profit the final price for units goes beyond what is considered affordable housing. I don't know if that's the case in Montreal or not.
With that said, even if affordable housing is not profitable for land/building owner, it's still "profitable" for the community around and in that future building. So from that angle, even if it's unprofitable for the land/building owner, it should be "profitable" for the public/government. And if that's the case, then it's kinda pointless to rely on the market to find it profitable enough to build affordable housing.
But then someone would say that would mean some builders won't make as much as they otherwise could which means line won't go up as much, government bad, free market good, fml... ☠️
In any case, I think we should put the market in its place and build affordable housing without waiting for it to consider it profitable. That's a perfect example where even creating new money can be a net benefit.