WH, I would not disagree. However, the reality is that if a controller is working to his/her capacity, then the only way they can manage their workload is to limit/restrict access to the CAS that they are responsible for managing; this is irrespective of 'right of transit'. This takes me back to my point that units must ensure they are properly resourced to meet the task.
David, an interesting proposition - I will put this one in the melting pot.