And exactly that is the flaw. Let alone using a linear operator (factor 4 between area and diameter of the sphere) to a non linear relationship (4th power). Again if you apply Stefan Boltzman, unedited with the spurious factor 4, and at albedo 0.3 (which is including clouds, which are non present in the null hypothesis) then you get a value of 88 degrees celsius. If you use moon albedo of 0.12, Stefan Boltzman returns 381.21 K or 108 degrees celsius as the equilibrium temperature in the zenith point where the full solar flux, all 1360 w/m2 hit the surface momentarily, and that is the forcing factor of the convection. Not the factor 4 division that gives -18C everywhere on the planet. It does not, by any means, earth is allowed to cool as much as it physically has to, emitting low freq radiation to space, totally unrestricted by the missing greenhouse effect. However the cooling earth surface does not effectively cool down the atmosphere, except for the lower most boundary layer, due to the lack of negative convection.