Hello AJ-EMT. You should be OK if you follow the United States Flag Code:
"§171. Conduct during playing
"During rendition of the national anthem when the flag is displayed, all present except those in uniform should stand at attention facing the flag with the right hand over the heart. Men not in uniform should remove their headdress with their right hand and hold it at the left shoulder, the hand being over the heart. Persons in uniform should render the military salute at the first note of the anthem and retain this position until the last note. When the flag is not displayed, those present should face toward the music and act in the same manner they would if the flag were displayed there. "
The flag code does not distinguish between types of uniforms or headgear. It says "Persons in uniform should render the military salute." It does not limit the military salute to persons wearing military uniforms. Uniformed police officers are not "military" yet they use the military salute when in uniform.