but nowhere does it expressly state that the intention is to regulate commercial photography and that private photography for personal records is allowed.
Agreed, but if the intention was really to stop people taking photos, a sign saying "PHOTOGRAPHY PROHIBITED" would be up there tomorrow, along with an automatic voice barking orders.
Also regarding T5, I always thought that all gates had access to International Arrivals but I now hear that the stands used for domestics (~ 501-506) do not and arriving international passengers are bussed. Did things change or are they not able to keep the flow sterile, even given all arrivals and departures are segregated.