A simple Google search indicates that the man was a journalist. There are several photographs available on the Library of Congress web site. He was unlikely to be an accredited diplomat. Journalists are covert gatherers of intelligence by definition and a USSR-based journalists was undoubtedly on the FBI counterintelligence radar. The Russians would be unlikely to use such a resource as a spy when they had accredited diplomats in the intelligence establishment who were protected by diplomatic immunity. They also had a significant establishment of agents in place at the time.