That old chestnut hey err... Walnut?
By that yardstick, we'd better move LGW 'coz every time I drive the motorway down there I get stuck in traffic.
Or move Slough 'coz the M4's always congested when I go passed....
From the data in the AC report & Highways Agency, LHR isn't the main reason for congestion on the western M25 stretch. Convenient excuse but not the cause.