“The paper is full of red herrings like that”
Oh really? what are the other ones?
In the whole document, "greenhouse effect" is misused. They are correct that it is not a "glass house" effect, but they measure a greenhouse (car) regardless. The primary difference is that the glass is one thin sheet whereas the GH gasses are the whole atmosphere. If the interior of the car glass were 71C and the exterior of the glass were 31C, then it would be a useful analogy, but it's obviously not.
page 38: "Furthermore it is implied that the spectral transmissivity of a medium determines its thermal conductivity straightforwardly" That is not implied by the previous quotation, which, although poorly worded, implies that the entire thickness of the atmosphere is the glass. There is no air trapped inside of glass that has specified thermal conductivity. There is only air with conductivity, convection, etc. The quoted author (Moller) does not imply otherwise.
This is followed on pp 39 and 40 by a bunch of poorly worded descriptions of the GH effect. For a better description see here: http://www.realclimate.org/index.php/archives/2006/01/calculating-the-greenhouse-effect/langswitch_lang/sw
page 59: the diagram shows top and bottom of atmosphere radiation budgets. The numbers are approximate but not inaccurate or physically impossible to determine. For point 1, they are not intensities, they are fluxes. For point 2, the sidewards fluxes are irrelevant. Points 3 and 4 on the next page are irrelevant, the arrows are approximately representations of steady state fluxes, no more, no less.
page 66: nonexistence of global mean temperature. I guess this is supposed to be a metaphysical argument, since there is no such thing as average temperature, there is no such thing as an equilibrium temperature. But working backwards, there is a theoretical equilibrium temperature from the incoming radiation, earth physical shape without the atmosphere. The average temperature can also be measured, not like table 13, but with equally distributed satellite readings. The theory and the reality can be compared and have been successfully. There are obviously uncertainties and approximations, but the 33C difference (GH effect) is not off by more than a degree or two.