It is basically a stabilizer. Connecting the pair of adjusters next to each other will keep them straight up and down, and keep them from tilting at an angle. Adds a tiny bit of rigidity to the adjusters which you want for stability. The adjusters can make big changes with just a fraction of a turn, and the same can be accomplished by tilting the adjuster.
Next time you are trying to sync your carbs just take a screwdriver and tilt one of them and you will audibly hear your engine react. Having them TOO rigid and a thicker metal, would however make it so that each adjuster would lose some of its "independent" properties. They would be connected so firmly that they would essentially be acting as one unit, not two independent units. With a bit of flex they can add strength and keep them in the right orientation and also allow for independent adjustment.
If you really need that particular part, shoot me a PM and I will send you one.
- James