"Ungrateful murmurers who became bitter, feeling they were being mistreated." That's probably what the Pharisees and Jewish leaders said about the Christians when they walked away from their corrupt religion.
"The beliefs they disagreed with were biblical principles they didn't want to follow." In the case of "apostates" (active opponents) I would say they disagree with peculiar Watchtower interpretations of biblical principles; interpretations that twist and pervert those biblical principles and go far beyond what the Bible says. Those apostates have "carefully examined the scriptures to see whether these things are so" and decided the WTS is lying in an affort to gain control over the lives and consciences of people they beat into submission.
"They are led back to the nauseating teachings of Babyloin the Great." How many "apostates" join another church? Many give up religion entirely in disgust. Many may still accept JW positions on the trinity, etc, but reject the perverted leadership of the WTS.
"They speak abusively of glorious ones ... congregation elders and the faithful slave." Maybe that's because they resent being hounded and bullied and controlled by elders whose job is to maintain members in the firm grip of a cult. "Apostates" don't speak abusively of the faithful slave because they know there is no such thing. All doctrines are established by the religion's seven-man Governing Body, based on human reasoning. The GB is so deceptive they try to invent another layer of decision makers (the FDS) to create the impression it's somehow God directing doctrines.
"...forgetting from whom they learned these sacred things." The fact that JWs accepted certain teachings does not mean they are bound to accept them for life. The WTS forbids members from examining their teachings with other sources or listening to contradictory arguments. Once JWs gain the courage to disobey that command and discuss their concerns about illogical, contradictory doctrines with outsiders (and former members) they have every right to decide they were tricked and walk away.
A typically twisted piece of propaganda that claims dissenters are driven by pride and ambition, bent on dividing congregations. They create stereotypes, place labels on honest, sincere people who cannot conscientiously remain in a religion that lies to them and tries to control them. Dishonest, manipulative bastards.