I find it odd that you, a degreed atmospheric physicist would use such a site as your reference.
This isn't a science site, is it. Hmm...
However, I enjoyed it when they REPEATEDLY stated that the direct greenhouse warming effect of CO2 was an inarguable fact. You and Same Shit and JC456 and Skookerasbil and Crusader Frank don't seem to have accepted that. If you reject that premise, why do you (apparently) accept the rest of this argument?
Now let's address the article's claim that GCM models assume LWIR radiation will decrease with increasing temperature. First, this, as stated, is a violation of Planck's Law and SB. Higher temperatures yield greater radiation. The problem seems to be that someone has turned the terms around. If we take a body at some temperature and by some mechanism, reduce the total amount of radiation escaping to space, the body will increase in temperature. However, that is not what the greenhouse effect involves. Greenhouse gases SLOW the escape of radiation by absorbing and emitting LWIR and sending some of it back to the surface. Eventually, a body with a fixed level of greenhouse gases will reach equilibrium at some temperature above its blackbody SB temperature. If you increase the level of GHGs by some step value, outgoing LWIR will slow further, more will be reabsorbed by the surface and the temperature will begin to rise. That increase in temperature will increase radiation to space until the system is at equilibrium once again.
So, basically, I believe the data your article presents, is deceptive bullshit.