As you said in your post, he was legal. Therefore there existed no suspicion of illegality, and therefore there was no reasonable suspicion to detain.
You can be legal and smart, and you can be unconstitutional and stupid. You can without a doubt be outside the bounds set by the courts and the law. And you can make other law enforcement officers look bad as you work hard to discredit all the work they have done to be seen as guardians of the law.
You can make improper choices that negatively affect your career and bank account.
Years ago,in Colorado,the advice was"Well,open carry is legal,but if you show up at 7-11 and anyone calls in,you will be arrested for disturbing the peace"
Years ago, in Chicago, the advice was "Be black and walk around town at night and be found hanging from a tree in the morning."
The free advice given was worth every penny paid, as the law reads ...
18-9-106. Disorderly conduct.
(1) A person commits disorderly conduct if he or she intentionally, knowingly, or recklessly:
(a) Makes a coarse and obviously offensive utterance, gesture, or display in a public place and the utterance, gesture, or display tends to incite an immediate breach of the peace; or
(b) (Deleted by amendment, L. 2000, p. 708, 39, effective July 1, 2000.)
(c) Makes unreasonable noise in a public place or near a private residence that he has no right to occupy; or
(d) Fights with another in a public place except in an amateur or professional contest of athletic skill; or
(e) Not being a peace officer, discharges a firearm in a public place except when engaged in lawful target practice or hunting; or
(f) Not being a peace officer, displays a deadly weapon, displays any article used or fashioned in a manner to cause a person to reasonably believe that the article is a deadly weapon, or represents verbally or otherwise that he or she is armed with a deadly weapon in a public place in a manner calculated to alarm.
There's much more than "somebody done called it in" required to substantiate a Disturbing the Peace charge.
"When an LEO checks you out for carrying an AR,and he asks you to set it down,set it down.The LEO said,had he done that ,after some questions,he would have been on his way. " The cop just put out his version of the story, "If only he'd ......" is his excuse. You know you're not obligated to answer Officer Friendly's questions, right? You know that NOTHING you say can be used to help you in a court of law?
"Get confrontational and defiant with a cop,you will lose every time."
You may lose the battle on the side of the road, that doesn't mean you won't win the war in the courtroom. Cop does something stupid because he can't control his hormones or someone didn't 'respect his authoritay' doesn't come off well when he's the one being the respondent to a civil suit.
"Freedom can only exist in a civil society.We used to have more freedom and fewer laws."
And who do you think is responsible? Dan'l Boone used to carry a 5 foot long Kentucky rifle everywhere he went, the cowboy had his trusty six-shooter, it was the riverboat gambler and backstreet cutthroat that carried a concealed weapon, which is why concealed carry has always been regulated and open carry has traditionally been seen as the mark of an honest man.
Now, thanks to Officer Friendly and his abhorrent behavior, plenty of honest citizens are up in arms over such abuses of authority.