Quoting myself again, I got a response back from the author:
Now, since there were 6 caps for 750mg PA, maybe we can figure out which supplement was used.
-King doesn't use Mediator anymore.
-PhosphaMuscle, Epiq PA, PhosphaGrow SX-7, PA(7), and PhosphaBuild all have 5 caps per 750mg PA.
-Primeval Labs PA has 250mg "Phosphatidic Acid Mediator" per capsule. If that's 250mg Mediator (50% PA), and not 250mg of PA from Mediator, then you'd have 750mg PA per 6 caps, from Mediator, which matches the description. It also doesn't have any other ingredients like many PA products do that should probably have been mentioned in the study, and doesn't have the delivery system that Micro-PA has, which also likely would have been mentioned in the study.
-Micro-PA actually has 6 capsules per 750mg PA, but do they use Mediator?
Perhaps they didn't want to mention the specific product because the study found it didn't really work, and they didn't want to seem like they were against the product and didn't want any trouble/drama resulting from this.