It's a but amusing that he mentions that the movement in the rocker assembly is eliminated and that is an advantage.
Reality is it is that movement that can allow you to pull the support plate toward the air filter and ADD pushrod to tube clearance. Also the vendor speaks as though this is the sole source and likely main cause of valve train noise. There will be many disappointed folks when they still have valve train noise after this install and in worse case with interference between the pushrods and the upper tubes. A better way to accomplish this is with set screws IMHO. Also keep in mind with proper torque and moving the support plate against the side of the shaft relief there is compression of the aluminum support and the shafts are held in place that way, no add-ons. The set screws are just insurance. Again JMHO