I think someone is misleading you. Every assault on medical staff is by someone intoxicated? I do not believe you. (Unless your hospitals ONLY serve people who are high.) Patients with head injuries never assault? Delirious octogenarians never assault? Psych patients never assault? What a bizarre world you're in that only drug users assault medical staff.
Never expect a patient that is altered to respect a guy with a gun, but do fear them getting that gun from that guy (a past study on hospital shootings found that something like 50% of shooters in the ED got their gun from police or security; E.g. 2005 at St. Mary's Hospital in Newtown, Pa).
If you're (not you specifically) having to consistently put suspected opiate overdose patients in restraints then you're probably doing it wrong (e.g. too much naloxone too quickly).
So, I know I'm sounding like a ****. Basically, I'm trying to impress upon you why what you have said sounds not real (not saying you're making it up).
Sure. But, you have no duty to protect and care for someone who is not a patient. Up to a point, just because the patient is combative/violent does not mean you can just get up and walk/run away. You have a duty to protect a patient from harm to themselves or others, and just because some guy with a badge and gun is not present does not preclude you from attempting to control the patient. While none of us want to get hurt, it is an inherent risk of the job. When you are very over-powered or are being threatened with deadly force, certainly it is prudent to leave the scene.