No one else should play Thomas Magnum, a k a “Magnum, P.I.,” in the big-screen version of the ’80s TV series except for Tom Selleck, the actor himself says. “Look, I’m not being egotistical, but ‘Magnum’ is in about 100 countries,” he tells Parade. George Clooney, Ashton Kutcher and Matthew McConaughey have reportedly been considered for the role of the Hawaii private eye, but Selleck sniffed: “They can’t just buy a title and stick some younger guy in it. These things are quite real to audiences.” The mustachioed actor, 65, is currently starring in CBS’s “Blue Bloods.”