2. Even if your claim was true, barring some court opinion supporting your claim what you present could be mere coincidence. Correlation, causation, all that. Therefore you fail on the factual level as well as the logical level.
I think you will find that every time the courts have overruled executive privilege, an actual criminal investigation has been going on (with actual charges filed, a special prosecutor, etc). At this stage, Issa is not running a criminal investigation (nor may he even have the authority to do so).