And anger and the ability to identify and express your distrust and disappointment is a healthy thing. It's better than keeping quiet and living with a situation that says you are bad if you disagree with something you feel is unjust or just outright incorrect.
At the expense of speaking for ABibleStudent (and I know I may be wrong in interpreting what I read in their statement), I think perhaps that the advice was to stay "critical," not to become "cynical."
A cynic is one who attributes selfishness to everyone and that no one or anything is worthy of total trust or belief. One who is cynical, according to definition, is attributing malicious and/or exploitative motives to all acts, including honesty and bravery. That really isn't the way to live.
But being critical, to skillfully analyze one's motives or the reasoning behind something taught, believed or done is healthy. Sure, one can carry this too far and become cynical, but when it comes to ideologies that can change or alter lives there's nothing unhealthy with investigating.
People often trust the critical or truth-seeking individual, but people will end up avoiding and rejecting the cynic. If your experience under the shadow of the Watchtower makes you better at critical thinking, that's great. But don't let the that same experience with the JWs turn you into someone who refuses to see the good in others or who won't trust others who will like or love you for just being you. It can happen because the Governing Body tries to teach us that we aren't anything without them, not worthy of a God's love and thus not worthy of love from others.
Of all the lies the Watchtower teaches, that is the worst and the most irresponsible of them all. Never believe it.