It seems straightforward to you because you're ignoring everything that makes this not work.

Here's a big one: you can't put radiators in shadow because the coolant would freeze. ISS has system dedicated to making sure the radiators get just enough sunlight at any given time.

The ISS goes into Earth's shadow for ~45 minutes and then in the sun for 45 minutes, in 24/7 repeat;

this system would not be given such an orbit. Its trivial to decrease the cooling capacity of the radiators: just have an emissivity ~0 shade (say an aluminum foil) curtain obscure part of the radiator so that it locally sees itself instead of cold empty space. This would only happen during 2 short periods in the year.

The design issues of the ISS are totally different from this system.