Expert opinions are often based on economic models which use incredibly simplified assumptions and questionably appropriate mathematical techniques. At least this guy is willing to post his model for the world to pick apart.
Peer-reviewed economic models would have to justify their model assumptions in a more robust way, including empirical data where appropriate. I'm not an expert but I expect this is a good place to start: http://www.journals.elsevier.com/economic-modelling/
All models use simplified assumptions and questionably appropriate techniques, I agree - that is practically the definition of 'model'. However, a useful model should justify those assumptions and techniques using current research-level knowledge, and/or show how the model applies successfully to reality.
I see this model to be as useful to economic discussion as saying "the world is flat, plus or minus 5 degrees". It ignores all current work in the field.