Watchtower cannot honestly refute the claims of apostates, so they desperately resort to attempting to suppress the truth about the truth from getting to JWs by demonizing apostates and coaching JWs to censor out apostate information.
If what the apostates were saying were false, then the best way to deal with it would be to publish a book listing the specific claims of apostates and refuting each one with irrefutable facts and evidence. That would be the best way to deal with apostates, if they were lying, because it would involve inoculating JWs against apostate lies.
But Watchtower cannot do this without engaging in further printed lies, because apostates are telling the truth and truth cannot be refuted. When fighting truth the most you can hope to do is attempt to hide it and hide from it. This is why deceitful and oppressive political regimes always resort to the use of censorship - because the truths that expose them cannot be refuted. Watchtower is no different.
Truth is like an invincible warrior while the lie is like an evil, scheming weakling. A weakling cannot defeat an invincible warrior so his only option is to hide from him. And this is essentially what deceitful manipulative organizations like Watchtower do - they hide from the truth and attempt to hide the truth through the use of censorship.