Here is my reasoning: The anti-detuner device is not engaged UNTIL a given pedal is depressed on E9th, UNLESS the guitar has the device installed on the C6 neck as well.
Which I understand, is not too many. In other words, while it is availabe on both necks, most opt' to have it only on the E9th neck. Its cost just doesn't justify it. BE would be an exception, because he is one of few that plays more on C6 than E9th.
I do not know whether Buddy has it on his C neck.
In another thread, someone posted that bowing of the cabinet IS the root cause of so-called" cabinet drop, because E9th strings drop just as much when C6 pedals are pressed. He added that because the pedals on the C neck are closer to the middle, the drop would be even more. Or words to this affect. I have not thought about that in years.
So tell you what, I have a LeGrande II sittin in my music room. I am going to flat find out. I will let ya know later.
That WOULD prove it once and for all. My guess it, it 'taint so. IF it is, I will be the first to say it!

carl