What makes a public servant necessarily any more trustworthy or less than a citizen with a conceal carry permit (Ft. Hood anyone? Oklahoma state police? The various "Don't taze me bro" incidents.)? What if the police aren't on scene when you arrive?
Im sorry, but I am going to put more trust in a police officer than I am some random citizen I come into contact with. That's just the way it goes. Which of the two has gone through an extensive background check, psychological check, and hiring process to carry a weapon? I'll tell you that it's not the CCW holder. So yes, a public servant IS more trustworthy than a citizen with a CCW.
If the police aren't there, I will judge the scene as I see it. If I see that the patient has a weapon, I'll hold off until LE arrives. If I look and don't see an obvious weapon, than I will approach with caution, as everybody should do on every call. If I see a weapon while I'm close to the patient, I'll have to make the determination then. If it's on his person, and I don't feel safe, they can wait for treatment. If it's on their person and I do feel comfortable (not safe. You should NEVER feel completely safe), I will probably treat the patient until they give me a reason to do otherwise. If they openly say that they have a weapon on them, I'll ask where it is and make a decision about what to do. This could be as simple as saying "Okay, thank you for letting me know sir. Would you mind keeping your hands away from that area?"
It basically comes down to my safety and my partner's. If I see a weapon while approaching the scene, the patient will probably have to wait a bit. If PD is on scene, and I discover a weapon while treating the patient, I will have them take it into their possession. If they admit to having a weapon on them and PD is on scene, I will ask the CCW owner to relinquish the weapon to the PD to ease the flow of treatment. If I discover that the patient has a weapon and PD is NOT on scene, I'll make the determination about what to do then, as I stated above. If I do not feel comfortable, or I think something is wrong, I'm not going to let the door hit me or my partner on the way out.
By the way, the only person bringing a weapon into my ambulance (when I work on one) will be a LEO. If a patient has a weapon on them, they're not entering the patient compartment.