I am unclear how people in Pakistan installing solar to power their factories and air conditioning instead of using fossil fuels is a fatal flaw. It seems to me that it is a very good kind of flaw to have in the model.

Unless the model was assuming that Pakistan would simply have to do without air conditioning because they wouldn’t be allowed to run it on fossil fuels. In which case the model had an appalling flaw in it - in the moral sense as well as magnitude.