The first premise is reasonable. The second premise is so outlandish as to require dozens of other assumptions, optimistic outcomes for launch, and pessimistic views on the cost of earthbound systems.

I care about the environment and I think we can keep earthbound systems, and also reduce their impact. Making assumptions about the feasibility of launch and the economic absurdity of orbital compute, but not affording the same assumptions for what could be done for earthbound systems, is confusing?

And no, orbital compute is absolutely not far lower than earthbound in co2 cost. Because it doesn't exist at any scale. All orbital compute is solely dedicated to switching where it is best served. If you were to spitball numbers, are we even willing to assume orbital matches earthbound in compute total, dollar cost, uptime, or any beneficial metric?

The only metric I see is just slinging silicon into space.