Notwithstanding any other provision of law, a person holding a license as a private investigator or private patrol operator issued pursuant to Chapter 11 (commencing with Section 7500), Division 3 of the Business and Professions Code, or uniformed patrolmen employees of a private patrol operator, may purchase, possess, or transport any tear gas weapon, if it is used solely for defensive purposes in the course of the activity for which the license was issued and if the person has satisfactorily completed a course of instruction approved by the Department of Consumer Affairs in the use of tear gas.