Wth...
Ok, I'll wade in as the devil's advocate.
Domestic calls are highly dynamic, dangerous, and very difficult to predict. One party at least has "called for help" and assistance now legally must be rendered. Chances are very good someone leaves in cuffs depending on dept. SOP, local & state law. WHEN this happens, there is sometimes regret on the part of the complainer, who could direct their pent up anger at "the man". There's almost nothing worse than getting in between two arguing significant others. However.
Significant facts are that dispatch was notified that a person who identified themself and advised that they were armed was calling to report a crime. The officer arriving on the scene immediately identifies two males _NOT_ on the property, or in the yard/curtilage of the actual scene of the reported crime. While it is generally agreed herein that the officer was correct to "secure the scene", I argue this constitutes both a seizure as defined by the courts on 4th amendment grounds, and, an actual custodial arrest. No reasonable person after having a firearm seized and "locked in the trunk" of an officer's vehicle would feel "free to leave". Any suggestion to the contrary ( do a THR search before you pontificate ) would be utterly ridiculous.
"Darn! The MAN just took my gun. Oh well, I'd better go home."
The officer overstepped her bounds and authority in seizing the firearm of a(n otherwise) law abiding citizen who merely got involved to be a responsible person, doing what the law required of him. These persons were standing in a publicly accessible area "going about their lawful business", and were not "at the crime scene" or part of it. Nor were they showing any intent to become part of it.
Now, change the circumstances a little, having our two gents "going about their lawful business" but in the yard, at the door, on the sidewalk of the crime scene - the officer is well within their authority to secure the actual scene.
It is untenable on it's face to imagine that the mere arrival of law enforcement justifies the infringement of constitutional liberties secured by Amendments 2, 4 & 5 of the US Constitution. Even in such a situation as a domestic dispute, the totality of this circumstance did not warrant any kind of seizure given the events described.
FWIW, I was OC at a traffic incident in which the vehicle I was in was rear ended. Virginia State Police showed up. Got our info, observed us exchange info, told us we were done, could be on our way. THEN he asks "Are you LE?" - me: "Nope". Him: "Ok, have a good day Mr. Smurfslayer". me: "Thanks, you too". I know, I know... it defies Brady campaign propaganda, but really, there was no blood in the streets...