If they fired him for being a Jew or a Catholic or being a black man or a Woman he could and should sue and force the issue. All know this. So the 2nd Amendment is still a part of the Bill of Rights that would cover the deprivation of his or her rights (rights bound over in the case of womanhood or being black, Indian or any other "minority" by subsequent amendments)
It's time gun owners started using the law to their advantage.
Here in Jersey, the employee would be behind bars facing felony charges. The assailant would be a catch-and-release. Too bad he's not worm food. That's life in this commie state.