His is a model only in the sense that the incoming SW and outgoing LW can be analyzed for a particular column of air to determine net warming. Doing that for varying latitude columns is nice and gives you some general ideas. The problem is that the main parameter in the column is water vapor which can only be determined by modeling weather. In a sense Miskolczi makes the same mistake as the IPCC modelers in oversimplifying weather to a parameter or set of parameters. Then the argument devolves into whose assumptions are correct for which the answer is emphatically: neither.
If you don't have confidence in the IPCC's model, then why did you post that graph?
You don't see any plausible reason for the negative feedback in his alternative climate model. But I'm sure he had a good reason to put that in the model. We would have to read his paper published in Hungary to find the reason. It's not easy to deduce what the reason is because climate science is so complex. There are all kinds of physical processes going on in our atmosphere: reflection and absorption of EMR, transfers of heat from the atmosphere to land and seas, radiation of heat away from the earth by the atmosphere, land, and oceans, etc.. It's not simple and it's very difficult to model correctly. That's why we need to stop cap and trade immediately until we get the science completely figured out.