Answer: You are absolutely correct that the classic teaching with penetrating trauma is for torso related penetrating injuries. Nevertheless, the pathophysiology (exsanguination) is the same regardless of the anatomic location of the injury. For instance, if you bleed to death from a femoral artery laceration or a pulmonary artery laceration, the physiology of the patient is identical. The only difference is that the larger vessels are more centrally located therefore the likelihood of exsanguination from a head or a limb injury is far less than from a penetrating injury to the torso.
It is important to remember that the TOR remains a discussion point between a Base Hospital Physician (BHP) and the paramedic where the BHP ultimately orders the patient be transported or pronounced: by patching to the BHP it is not automatic that the patient is going to be pronounced!
To answer your question specifically, the SWORBHP Medical Directors believe that paramedics should follow the Trauma Cardiac Arrest Medical Directive for any patient who arrests from penetrating trauma regardless of the anatomic location of the injury.