Beam me to Planet Gore !
Ah, the joys of modeling...
I fail to see the point. He describes exactly what was done. Certainly if stratospheric chlorine levels had been higher, there would have been a corresponding effect on ozone, and the concentration of ozone in the stratosphere has climate feedback effects. This paper looks at what the climate feedback effects might be if chlorine concentrations in the stratosphere had been higher.
What other modelers do now is try to do the same thing with a different climate model formulation, and see if the results generally agree. If they do, then that's important information regarding how well they understand the climate system. If they don't, then they start trying to find where the models are different, and this helps to determine where the uncertainties are.
That's how science works. It's too bad the writer had other fish to fry.