Hey Stuck!
The WT is "framing the debate" about those who leave. In effect, WT says there are only two options: You are 'upright' if you stay with the Org. OR, you are "bitter, negative, et al . . . if you leave. They don't want their readers to think that there might be another possibility.
They do the same with partaking at the memorial: You either accept the truth (as they teach it) and don't partake, OR, you are emotionally/religiously disturbed if you do. There is no possibility that someone might simply accept Jesus' instructions as being for all. They don't want anyone to even consider that possibility.
Bobcat