Exactly, it calculates the horsepower. It isn't something that can be measured on it's own.

I can see your point about the Dynojet not measuring actual torque because they know the variables in play and they already know how much torque it will take to spin the roller x amount of times in y seconds. But they are still using torque and RPM to determine the horsepower of the car on the dyno.

It's not really worth arguing over since it's all symantics in regards to how Dynojet wants to advertise their product.