The ISS's radiators weigh thousands of kilograms to radiate around 70 KW. He's talking about building data centers in space in the GW range.

Assuming he built this in LEO (which doesn't make sense because of atmospheric drag), and the highest estimates for what starship could one day deliver to LEO (200 metric tons), and only 1 metric ton of radiators per 100KW, that's 50 launches just to carry up the radiators.