Two comments:
1- Nintendo isn't the least green tech firm, they simply didn't share their information. While that can be seen as a bad sign, it's not enough to warrant that conclusion.
2- If they took electricity usage into account, it would likely make up for any additional greenhouse gases emitted during production. I recall reading that the Wii uses about 10 times less power than the other consoles.
My Mario Kart Wii friend code: 2707-1866-0957