How do we know that he or anyone for that matter changed without a reasonable doubt? Sanju got 6yrs due to the nature of the crime he commited. Punishment totally depends on the kind of crime you do. Thats the job of law to make sure every criminal gets some sort of punishment. Just because he played nice roles doesn't make him a changed person per say. I'm sure many of us feel sorry for him after seeing him play better roles.