check again the script post, I've changed the Update rate.

Relevant code:

 private void Update()
        {
            //Note: Start with a conservative value here
            //a high value slows down.
            const int interval = 30;
            if (Time.frameCount % interval != 0)
            {
                //don't run yet
                return;
            }

The above code runs the code once every 30 frames. Start with a conservative value, until you reach the breaking point

Am I doing this right?

If you have the RotNew assigned to joints "0" and "2" ...

Why the question ? Is not compiling or moving ?

*** EDITED ***

1. Don't forget the conservative interval, to avoid clogging the Unity.
2. Check the Joint names and values in the debug windows, confirm the joints names are correct and confirm the values are between -90/+90

Also using your definitions, I am getting this if I rename the second BioJoint... I changed the Name of Joint 1 to "Hello World", Joint 0 ist still named 0.

This is the naming convention... So Joint 0_X shows as 0, Joint 0_Y shows at Hello World...which is the name of the next Joint in the Hierarchy, and Joint 2 does not show at all!

So "0" is being matched or not ? "HelloWorld" is not defined, so you see the values, but no servo movement.

Edit...Joint 2 shows with his correct name Joint 2!

There is no servo movement at all...