I don't know if certain media and leftists *believed* him, but they certainly wanted him to serve as a leading anti-war voice and Bush administration critic.
IF those media types knew that he was involved in activity that made him susceptible to blackmail, yet presented him as a legitimate spokesman for "the cause", I consider them, well,--I hesitate to use the word,--I'll say I consider them in the same category.
And perhaps it was thought that if he said he voted for President Bush that would make his criticism more impressive. (I, of course, have no idea who he voted for)