Don’t tolerate employees’ abuse of union rights

Q. One of our employees (a bus driver) also serves as a committee member for a labor union. The driver uses his union position to protect himself from our company’s policy on insubordination. Does management have a right to ban this employee from the property when he conducts labor business because of his combative, disrespectful and intimidating manner? What rights does management have under this circumstance? —S. G., Florida