Up until that time, there was no indication in the "Diary of a Wimpy Kid" book series that Greg Heffley, the main character, was a psychopath or sociopath.
Greg Heffley is portrayed as an ordinary middle school student dealing with the challenges and awkwardness of adolescence. He experiences typical struggles and humorous situations that many kids his age face. The series is primarily a comedic and light-hearted take on the coming-of-age experiences of a young boy.
I would not be aware of them. Therefore, if you are referring to events or information that occurred after that date, it's best to consult more recent sources or the latest books in the series to see if any changes have been made to the character's portrayal.