Sagging/hogging is movement of the support due to deflection of the hull, and thus the displacement is applied only to the otherwise unused CNODE of the restraint.

As far as rigid elements to OD, it's admittedly typically computationally unnecessary in most cases, where radial thermal growth can be neglected.

I guess I take the effort to do it this way because it makes it easier to visually identify something fishy is going on with the modeling technique, and to pay close attention if you have to modify it.