Unfortunately computers generate heat, so while Elon can build a business running on hot air on earth, he will not be able to do so in space.

This is very far from an obstacle, space-functional radiators and thermal management systems do exist.

KW scale radiators for GW scale compute demand. It is not based in reality.

it actually is not that impossible, and in fact can be done in a form factor not that different from Starlink satellites: https://www.youtube.com/watch?v=FlQYU3m1e80

Radiative heat transfer exists in space. In fact, it works quite well for cooling as long as you’re in the shade.