Every single satellite has sufficient cooling for its power production, otherwise they would be frying. Waste heat from a GPU is not materially different from waste heat from an amplifier. That's not cooling entire racks, but I don't think anybody talks about putting entire racks in space anymore.
I'm very much pro nuclear, but a solar cell in a sun synchronous orbit is pretty great too and eliminates most battery requirements
I very much doubt the economics of this makes sense, but I don't think a lot of your criticism is valid.
But here we're talking about putting data centers in space. It means stuffing as many gpus as possible into each satellite and running them at constant max power.
I don't think they can avoid a Kessler cascade at that scale, but if launch costs were cheap enough (questionable because Musk habitually overpromises and underdelivers, but not inconceivable as sometimes he succeeds too) then patterning each of those million on Starlink satellites is essentially viable.
Cooling per unit is also basically fine, people make incorrect associations with the ISS without removing the bits of the ISS that aren't computers, including all the humans who die from heat at lower temperatures than chips can run at.
It comes down to the price to orbit vs. the price of not going to orbit. I don't trust Musk for the former, because even with the impressive demonstrations seen in Starship, they need to make that vehicle fully reusable to get the cost low enough to be an improvement over batteries and more PV and scattering the same count of units randomly around the desert in Arizona, Nevada, etc.
Christ. I thought we had seen the last of the Musk-tards.