In my class that I teach for college healthcare courses, I asked my class if he should have to state this publicly due to his stature of being in the public eye. Mixture of yes and no answers. For the record, for the safety of his sexual partners, the outreach of doing this publicly will help.
He should only have to disclose he is hiv+ to his sexual partners or in other potential 'risk' situations (getting surgery, blood analysis, etc). Doesn't matter if he is a nobody or the most famous person in the world, it's nobody else's business.