It may be a mitzvah to expose heretics as whay they are: HERETIC. Not to spread libels about crimes, especially if those heretic are still halachically Jewish. And anyway, no mitzvah applies, when it endangers Jewish security. Even if it were allowed to make false accusations against an heretic, you cannot do it if it endangers the whole Am Yisrael. How can you spread the false suspicion that some Jewish orgs. (even if heretic) may be involved in child sexual abuse?
In fact, some Catholic priests have been accused of child molestation, and some of them may be really guilty of the crime. But nobody would even think demanding the destruction of Catholics, let alone all Christians!!!!
But if someone spreads the libel against a Jewish group, then all Jews and those who support them may be attacked!!!!!! Have you forgotten the anti-Semites?
They are eager to take anything at their reach, to use against Am Yisrael, and those who support it!!!!!!