Without protection or macros, you are left with the AutoTextList field. I don't know how you can make them aware of the AutoTextList choices. I suppose you could make the default choice something like [Pick one here]. That is, use blaring different formatting to indicate that they have to do something. You would want the formatting to be directly applied formatting in the AutoText entry, not applied to the field itself. That way, when the choice is made, the formatting returns to normal.

Otherwise, a document can have some Sections protected for forms and others that are editable.