Howdy Gentlemen!
Interesting debate we seem to have here.
To me, the basic elements are:
1. OP open carried into Best Buy.
2. Best Buy manager approached with questions.
3. OP answered, best he could under the circumstances.
4. Best Buy Manager asked his former LEO security guy about the legality of open carry.
5. Former LEO gave his opinion based on lack of knowledge of the law.
6. Based on what he thought was reliable information from the former LEO (after all, he should know the law, right?) he asked OP to leave.
The basic problem is that their stance took root in the opinion of a former LEO who got it wrong.
The only legal precedent to support open carry, spelled out without ambiguity and clearly stated is Article 2, section 13 of the Colorado Constitution. It isn't spelled out in any CRS of which I am aware.
The basic issue is that the Best Buy manager acted on the basis of what his former LEO security guy said.
The quickest, easiest way to dispell that mistaken information would be to show A2/S13 and ask for his LEO to provde any CRS contrary to that specific statement of a right to open carry. Unable to so do, he'd soon be faced with an opportunity to recant his former opinion.
Then again, as I mentioned earlier, the Adams County Sheriff's office website, section on Concealed Carry Permits, FAQ's, states very clearly that OC is legal in Colorado with few exceptions.
Maybe that particular page might serve the purpose. But the location in question is not in Adams County, and I don't know of another LEA that states the reality so clearly as does Adams County... aside, of course, from the Colorado Constitution A2/S13.
You can view it here:
http://apps.adcogov.org/sheriff/chp_main.html
Do I need a concealed handgun permit?
By law, you are not required to have a concealed handgun permit to possess a handgun concealed inside your vehicle, your home or your place of business. You may also carry a handgun visibly on your person without a permit in most public places in Colorado. There are exceptions, such as posted areas and government/school buildings, and/or cities with ordinances forbidding that practice.
Perhaps that could serve as a "write up" of some sort.
Blessings,
M-Taliesin