First thing to try is cutting a screw driver slot in the end of the stud with a separating wheel in a dremel tool. As you start applying torque to the screw driver, have someone else tap on the end of the handle with a hammer - the longitudinal stress in the stud breaks the friction in the joint and allows the stud to start turning. Don't hit it like you are forging iron, just firm taps.
If that doesn't work, and the aluminum part is ultimately replaceable and no one's life is at risk if you over heat the part slightly, have your assistant apply gentle heat to the aluminum surrounding the stud. The coefficient of thermal expansion of aluminum is about 50% greater than steel, so this will increase the hole diameter and loosen its grip on the stud. A shop heat gun will work best, fire should be used carefully, and even your daughter's hair dryer may get the part hot enough. Then redo the first step with the screwdriver and hammer routine.