why?

because there's a little caveat to the Environmental Assesment process that if there is a private component to the generation proposal, it is automatically exempted from a full EA, and only a "self-assesment" is required. I discovered this fighting the Portlands Energy Centre for the past 2 years.

As well, there is a "memorandum of understanding" brought in by McGuinty that prevents OPG from owning or operating any renewable generation.