I see the assembly not as turnbuckle, but shackle, there is a difference. A turnbuckle is used to take up slack, not necessary when the cabling is constructed as “lockclad”. In any case, one lead loosening in a turnbuckle tightens it’s counterpart. I have a picture in the manual.
The attachment of the command cable is made by threading a swaged terminus into a collet, which is placed into the opening of a shackle. The collet is then locked into the leaves of the shackle with a pin. The end of the cable can not rotate. If you are familiar with “push pull” controls, you would know that the cable resists “spinning”. The entire length of the cable would “Flemish” into a coil, which is not possible.
Cable slack is addressed specifically by Lockheed with this (patented?) cladding.