The “security volunteer”, a title which means nothing, had a gun. Why should he be allowed to detain an individual who also has a gun for the sole reason of them having a gun?

No, either Americans have the right to wield guns, in which case y’all need to just accept that and realize that assembling a gun during a protest is legal and therefore not suspicious Or, y’all need to realize that your gun laws and culture are incompatible with modern society, and do something to change them.