Sec. 9. Notwithstanding section 6 of this chapter, this chapter does not prohibit a public or private employer from:
(1) regulating or prohibiting the possession or carrying of a firearm by an employee during and in the course of the duties of the employee on behalf of the employer or while on the property of the employer; or
(2) enforcing a regulation or prohibition adopted under subdivision (1).
However, a regulation or prohibition adopted under subdivision (1) may not apply to a firearm stored or transported in accordance with IC 34-28-7.