The Citadel will begin AIDS testing of all applicants and of cadets who volunteer, and those who fail can be rejected by the Charleston, S.C., military college or expelled, the staff physician says. A survey by the school newspaper, the Brigadier, indicated most cadets favor the policy, which was announced Oct. 20 and will be implemented later this month, Dr. Joseph C. Franz, the college physician, said. However, an editorial Friday asked whether excluding cadets from mandatory testing defeats the policy's purpose of maintaining an AIDS-free campus. It also proposed that Citadel staff members undergo testing. Mandatory testing will be restricted to applicants, Franz said.