A sheriff's deputy who is often on-call for incidents at smaller California airport told me they are generally encouraged to keep their distance from the TSA unless explicitly summoned due to past incidents where their presence seemed to encourage unwarranted escalations by the TSA where they felt there was nothing appropriate they could do but turn around and walk away. They also fear deputies witnessing activity at the checkpoint requiring them to arrest on-duty uniformed TSA and having done that once for an outstanding warrant and the ensuing shitstorm from TSA management he said ignorance is bliss. The checkpoint is federal territory and they want as little to do with it as possible.