Jews are supposed to be a “Goy Kodosh U’Mamleches Cohanim,
a holy nation and a kingdom of priests.”
A Jew appearing on America’s Got Talent in front on non-Jews, singing non-Jewish songs, competing to go into non-Jewish show business, is not part of a Torah-dik Jewish lifestyle.
A Jew does not sanctify G-d’s Name by appearing on a show where he has no business being, in the first place.