Hi,
What did you want him to do? He was in exile. He may have thought that he would never be able to return to America. By the way when Vito said to the Commission that he had to make arrangements to bring his youngest Son back he wasn't kidding. In the book they made a deal with a prisoner on death row. The Corleone's would provide for his family if he took the rap for killing McClusky and Sollazzo. That is how Michael was able to return to the United States.

Paul