Notwithstanding any other provision of law, a person holding a license as a private investigator pursuant to Chapter 11.3 (commencing with Section 7512) of Division 3 of the Business and Professions Code, or as a private patrol operator pursuant to Chapter 11.5 (commencing with Section 7580) of Division 3 of the Business and Professions Code, or a uniformed patrolperson employee 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.