As MaRS is a public/private project, it will not be competed until they are confident they can find enough tenants in the private sector to make the project viable. This project, however, is all Queen's Park, and as such has built in tenants.
I don't mind the set-back, as most of Bay St. is like that anyway, it's not as though it will ruin some lovely curtain wall. It is a shame Bay St. wasn't built like that in the first place, though.