Favorable bias? I wouldn't say that. As a historian I feel it isn't ethical to attribute bad motive where other explanations suffice. Sometimes motive is 'bad.' In our books we point to several instances. In volume one of Separate Identity we point to L. A. Allen's apparent sexual relationship to one of the Watch Tower evangelists, but we use her own words to 'go there.' We point to Russell's self view that in the period we cover [up to 1887], he was God's special agent, a teacher of teachers. But we use his own words to do that. We point out that Barbour was a thief and a liar. But we use his own words to do that.
Attributing motive where there is no firm evidence is wrong. And doing so would make us like E. C. Gruss who simply made up his 'history.'
Many on this board feel hurt by the Watchtower. I understand this, and my own experience with Witness elders is almost entirely negative. But some of those who feel hurt express themselves irrationally. Assume someone is disfellowshipped for what? Sexual issues will do. They did not wish to live the life of strict adherence Witness culture demands. That is their choice. Personally, I don't care what others choose to do as long as it does not hurt others. But Witnesses believe they must intervene. So they disfellowship. Exclusion from a group is hurtful, and disfellowshipping is supposed to hurt. The goal is to make the 'bad boy' repent. In most cases it doesn't work, and the expelled person is resentful.
When we're resentful we tend to be irrational. So, let's say our 'bad boy' had multiple partners. That's not the Witness way. He likes having indiscriminate sexual encounters. Does he really want to be a Witness? Well, he doesn't want to behave as one, but he may like that feeling of belonging and he may want to stay within the fellowship. Exclusion brings with it the feeling that he is less than he was. In fact, nothing has changed. He is worth exactly as much before as after. But the feeling of rejection is still present. There is often a transference of blame. "Sure, I kissed ten girls today, six of them underage, and probably I shouldn't have, BUT they said I'm worthless and threw me out and my own mommy won't talk to me!"
Okay, I know that's extreme, or I hope it is. But humans tend to transfer blame for faults.
There is also the feeling that one has been misled. The Watchtower suggests that life within its fellowship is a near paradise. It isn't. People are what people are. Every fault individuals had before they were Witnesses, or the underlying causes, remains. One may have given up smoking, for instance, and never cured the underlying addictive behavior. So expectations raised by Watchtower doctrine cannot be met within their fellowship. There is nothing so bitter as believing you were lied to.
Watchtower authority structure is such that adherents expect ideal behavior from those filling authoritarian office - elders and such. At conventions, instead of thanking God for the 'spiritual feast' the chairman thanks the Governing Body and everyone applauds. They set their members up for disappointment. Adverse reaction to this often comes slowly. Old Goat who used to post here lives across the Columbia River from me. I know him well. He was a Company Servant back in the Day, then Congregation Servant, then Elder, Convention speaker, appeal committee choice. But over the years he associated numbers of incidents accumulated that could not finally be resolved. He simply walked away though nominally 'in.' When saturation occurs, there is a reaction. Again, one may want to say and think the worst of the person or organization they see as cause.
But we shouldn't say what is false. Ethically and morally we should not attribute motive where the facts do not sustain it.