Remember what he covered in the car wash operation that led to the release of Lula?
Even if he could show anything that could take Alexandre down, there were still all the other judges and the judges waiting in line to replace them. Alexandre already said it's his job to ask to make this procedure, so unless the system is changed, everything stays the same. When people realize that maybe things change.
https://youtu.be/4orlWZeF6sg?t=3m39s