Colorado constitution is irrelevant. Maybe a summary of OC law from a reputable source....Just to show that it is legal. Maybe take a friend...Volunteers?
You are ASKING that he change his policy to align with corporate policy. If he refuses this polite request then you go back to corporate and escalate.
Howdy Kingfish!
I don't believe that the Colorado Constitution is in the least irrelevant, especially in this particular case, with the former LEO security type being who they relied upon for the legality of our friend open carrying. He stated he didn't believe it was legal. Ergo, the stipulations found in the Colorado Constitution in Article 2 would be keenly relevant as they form the basis of Colorado law:
Section 3. Inalienable rights. All persons have certain natural, essential and inalienable rights, among which may be reckoned the right of enjoying and defending their lives and liberties; of acquiring, possessing and protecting property; and of seeking and obtaining their safety and happiness.
Section 13. Right to bear arms. The right of no person to keep and bear arms in defense of his home, person and property, or in aid of the civil power when thereto legally summoned, shall be called in question; but nothing herein contained shall be construed to justify the practice of carrying concealed weapons.
I've been following this thread with some interest to see how the OP decided to resolve the situation. I've been fascinated by some of the give-and-take. But it sounds like it is time for a basic Civics/Government lesson in Colorado.
Your State Constitution, like the Federal Constitution, imposes limits on the behavior of the government. It cannot, and was never intended to, control the actions of private businesses. When dealing with Best Buy you have no federal 2A rights, nor any Colorado Section 3/Section 13 rights. What you have is the right of the business owner to set and enforce rules so long as they are not blatantly illegal and do not violate certain rights of certain specified minorities who are being protected now because of past discrimination conducted under the power and cover of then-existing laws. Gun owners in general, and Open Carriers, are not one of those specified minorities. If you are a Black/American Indian female head of a TANF/SNAP-eligible household single lesbian transgendered quadrapelegic mentally challenged Aleut-Samoan/Pacific Islander owner of a business with more than $10,000/year in income from state contracts (and I'm sure I missed a few) who legally owns a handgun and wants to bring it with you to Best Buy or any other business while the store either posts signs saying "No Firearms" or verbally tells any customer seen with a firearm to take it outside, there are no constitutional rights that are being trampled on when Best Buy/other business does so.
Maybe you can go back to discussing how to negotiate with te Store Manager and educate him on both corporate policy and the truth about OCers being 17 times more law abiding than the local cops, as well as 35* times less likely to shoot anyone during their lifetime.
stay safe,
*that last one is admittedly a SWAG, based on a very fuzzy memory of some statistics I saw somewhere once upon a time. Someone could read John Lott's book and probably find a solid statistic from (at this time) more than a decade ago. There are more firearms owners now than when he wrote his book, but the percentage of firearm owners who have shot anybody is even lower now.