Actually, it can. Especially if safety considerations are involved (e.g. a weapon, etc.). The fact is that an employer can set the terms and condtions of the workplace much as it sees fit. For an employee's part, they can choose to continue to work for the employer or not.The above holds true unless such an action on the part of an employer would violate the terms of the company's own policy or the terms of an employment/union agreement. Also, this action cannot be the result of actionable discrimination.