The “armed rent a cop” at greenfield RMV is a retired corrections officer, and the Chief of police of a town, and a Sergeant on another police force. More than qualified to have a Glock on his side. I don’t think you can open carry as a security guard in MA unless you are a currently sworn law enforcement officer. I think your experience boils down to an implicit bias you have against officers. Have you had bad experiences with them in the past? Individuals who regularly encounter police officers, are usually encountering them because they are having a bad day, doing something illegal, or regularly engage in illegal activity. Let me let you in on a little secret, they can’t read your mind. They are trained to read your facial expressions and body language however. Look past the uniform, they are just people. If you smile and say hi when you encounter them, they will most likely respond in kind.