They are unleashing hate because their cult mentality is in control. They spew their venom because they suspect they are wrong and can't stand it. It's like children who cover their ears and say la la la la la, because they don't want to hear. They are afraid that the organization they revere is full of lies and they know it. They are afraid.
I know because I used to be like that. When faced with a former dub, my defences would go up, I would actually be afraid, because the cult conditioning was so strong. Fear of Apostacy is very deeply ingrained in most JWs. I didn't come here until eight years after I left, it took that long for the fear to go away. I had believed all the nonsense that apostates were bitter, unhappy people who want to tear your faith away. It's so silly when you think about it, what could anyone do to another to take away their faith? It's just words, if someone's faith is true, it should stand up to opposite viewpoints.