If he were a doctor instead of a hedge fund manager, the hyper-intense Steven Cohen would probably not be known for his bedside manner. But what the founder of $12-billion-in-assets SAC Capital Advisors may lack in warmth and fuzziness, he seems determined to make up for in charitable impulses. A $50 million grant from his family foundation underwrote a newly opened pediatric emergency department at New York Presbyterian Morgan Stanley Children’s Hospital on 166th Street.