I don't fly any of Frank's products these days, but if you did not have a switch easily operable on the lever, how would you deal with a governor runaway failure? The governor on the Robbos seem to be pretty reliable, but any well-engineered system needs to enable the pilot to cope with failures.
You could always grab the twist grip, but you would then need a third hand to pull the CB to make things "safe".
If I understand the original question, then I see what you are getting at. It would be very easy for an inattentive pilot to let the RPM rise to 80% and then suddenly get flying RPM without warning - there have been a number of accidents involving early/inadvertent take-off of students/low-time pilots as it is. This would seem to me to make the problem worse.
I don't have easy access to the RHC paperwork - can anyone who does explain the reason behind the change?