What invented constraints? We've been chasing nuclear fusion since long before we really cared about greenhouse gas emissions. We want 'cheap and plentiful power'. Greenhouse gas intensity is a recent addition to the set of goals. It doesn't replace the existing motives, and to claim otherwise is greenwashing.
> What we as a people need is a fusion plant that costs less per KWH than a fossil fuel power plant with tariffs to account for the cost of the carbon dioxide, but still about as expensive as a fossil fuel plant where the carbon is free
That the fusion plant can't be too expensive, or too cheap.