I'm not sure if I'm reading this correctly, but is it saying any Strip not marked on a WAC should, instead of calling on 126.7, use the Area Frequency?
What now happens if you have a Strip that is not marked on a WAC but is close to another Strip which is? You could quite potentially have a busy marked strip making calls on 126.7 as normal and another nearby un-marked strip making calls on the Area Frequency?!