For what its worth, if they go for this, they'll probably sweep up anything with trigger slap. So watch out, owners of AKs, and CZ75's with the original trigger.
I don't think this is the case at all. If you keep constant pressure on a CZ or AK and get trigger slap, you still have to consciously release pressure on the trigger then reapply pressure before the gun will fire again.
The FRT forces the trigger into the reset position
in spite of your pressure on the trigger to the rear, then allows the trigger to move rearward again once the bolt has gone into battery. The pressure your finger exerts on the trigger is constant, just as the pressure exerted on a full auto trigger is constant. The only difference is the amount of trigger movement during the action cycle period.
As a thought experiment, tie one end of a string around the trigger, tie the other end of the string to an appropriate weight that will activate the trigger, load the rifle, point the rifle vertically so that the weight pulls the trigger back, and see what happens.
With the FRT, the gun will continue to cycle until the ammunition is exhausted, although the weight will bob up and down. It is my belief that the ATF will contend that since constant pressure on the trigger results in more than one shot, the FRT constitutes a machine gun.
Rare Breed (and Wide Open Triggers, another FRT manufacturer) contend that since the trigger was forced forward into the reset position, the subsequent rearward movement of the trigger after the bolt goes into battery and releases the trigger locking bar constitutes a separate function of the trigger as defined by
26 U.S.C. § 5845(b).
Here is an animation of Rare Breed's FRT in action, so you decide for yourself if the shooter is making one function of the trigger, or separate actions for each shot fired.