What's wrong with dispatcher asking a few questions of the caller, such as: Is he threatening anybody? Is he pointing the gun at anyone? Does he seem angry? What is he doing right now? What is he saying? If there is clearly no issue other than an individual lawfully carrying a firearm then there is no reason to dispatch whatsoever.
And this reply should be in the 911 call response manual in every open carry jurisdiction! Under "MAN WITH A GUN" section... subsection (page 2) holstered firearm...
For a method of civil disobedience, folks could... NAY... SHOULD call 911 to report every uniformed officer open carrying in public. They are no different than us! Many are not as mentally stable as most gun toters and MOST leos do not fire near the rounds down range in practice as we do.