Does anyone know of a way to only move the active field in the form view, and "freeze" the columnar view?
Pretty sure you cannot. A split form is basically 2 views of the same thing, albeit the datasheet half represents all of the data associated with the fields from the other part of the form. That is, both halves refer to the same fields and if you select one in either half, you select it in both. The only way to prevent it AFAIK, is to lock the controls, which would be pointless.
The way to prevent the behaviour is to have a form/subform relationship instead of a split form.
The more we hear silence, the more we begin to think about our value in this universe.
Paraphrase of Professor Brian Cox.