You did not phrase your article as if it was obvious to you that this is not PD. Throughout your article, you referred to this as a "PD tournament" and "playing the PD".

So you're trying to model real-life agents in PD-like situations. Real-life actors generally don't face PD, but face a variant PD+I, where I is infrastructure that tries to induce agents to cooperate. Such infrastructure generally works through incentives, disincentives, probabilities of discovery, etc. The justice system, traffic police, even religion are examples of such PD+I infrastructures.

Each of these infrastructures works differently; in the case of religion, radically differently. I guess religion might be the closest real-life example to your source code inspection proposal - people do appear to cooperate more with others who share their religious beliefs. Other infrastructures, such as the justice system and traffic police, do not appear to be captured by your model.