Wondering what the environmentalists will have to say about this.

More of what they're already saying: "We decide what you can use electricity for."

Why? For Super AGIs with continuous ML/inference (aka artificial brain)?

As far as I know those models do not exist yet. Only models with a split between ML and inference (going to be really hard to get weight stability without a "sleep" regime).

OpenAI is betting on scaling, which means using more compute per request. More users times more compute is a lot more compute needed. We don't need to assume specifically what techniques will be used.