The Watchtower censors information. JW's are led to believe the Watchtower is protecting them from leaving 'God's Organization' and joining 'Satan's Organization' (i.e. everyone else).
They have been teaching this since 1925. The intense mental programming for almost a century causes JW's to remain loyal and fear the Watchtower as if they are God. The Watchtower gives JW's only Two Choices
The true reason for censorship is not to protect JW's. If the Watchtower had nothing to hide, censoring information would not be necessary. Censorship protects the Watchtower from losing members on a massive scale. 
'Apostates' refers to JW's who leave their religion.
Here's what the Watchtower says about 'false teachers' (i.e. anyone who disagrees with the wT) and 'apostate' former JW's.
'What must we do to avoid false teachers? We do not speak to them or invite them into our houses. We also do not read their books, watch them on television, read what they write on the Internet, or add our own comments about what they write on the Internet. Why are we so determined to avoid them? First of all, it is because we love “the God of truth.” So we do not want to listen to false teachings ...' [WT, July 15, 2011, Article: "Will You Pay Attention to Jehovah's Clear Warnings?", p 11; par 7]
The Watchtower also says JW's must not come in contact with former JW's (apostates) because mental disease is contagious and they could die! The Watchtower says, ''Apostates “quietly” bring their ideas into the congregation, like criminals who secretly bring things into a country. ... If we follow them, we will leave the road to everlasting life. ... The warning from the Bible is like a warning from a doctor who tells you to avoid a person who has a disease that may spread to others. The doctor knows that if you get this disease, you will die. The Bible says that apostates are mentally diseased.' [WT, July 15, 2011, Article: "Will You Pay Attention to Jehovah's Clear Warnings?", p 11-16; par 5-13]
'No matter what false teachers say, we will not follow them! Those who listen to them will be disappointed. We are determined to be loyal to Jehovah and to his organization.' [WT, July 15, 2011, Article: "Will You Pay Attention to Jehovah's Clear Warnings?", p 12; par 8]
1. Censorship is not necessary when there are no secrets. When our faith is built on a solid foundation we have nothing to fear. Consider the reasons why JW's are not allowed to do independent research by reading our articles.