Now in the course of that, one can do as Racer suggested and have an easy time of it OR they can turn motormouth and try ordering the police around while ignoring their very reasonable commands to reholster/lay weapon down. In that case, it would turn into the public having an expectation that police officers are Kreskin the Magnificent, able to know the thoughts of any they encounter. But that's not so, and court cases are awash in situations where officers articulating a reasonable fear of danger were not punished for drawing a weapon and in some cases using it.
They have no way to know if those two were completely disarmed or they only laid down a shotgun and still have something else on them. I don't think it's reasonable to force an officer to reholster on command of a citizen being investigated. What would be next, telling them to put the handcuffs away, you'll follow them to the jail?