"Chilling effect" has always been a profound term for me, because I imagine the "cold" (numbness really) sensation a human body often senses when something truly awful (disembowlment/dismemberment) occurs. The body's way of protecting itself is to go "cold", and in many ways that's exactly the effect taking place here, as well.
There's also an undeniable part of this conversation that rarely gets addressed simultaneously, and I'd like to see it sussed out more in concert; what about the folks who are doing Evil in these private channels? It's unacceptable to me that TOR gets used for child pornography, and it's unacceptable to me that my government finds out I'm gay before I come out to my family.
I don't want to provide those who would do Evil any safety or quarter. I also want to give people a powerful shield to protect themselves against judgement and persecution from the public and sometimes the law.
We should talk about achieving both of these goals, but we generally don't.
It would be better to ask whether someone, who is not a willing participant, is harmed by the activity. That's easier to establish.
The fact is, our collective idea of good and evil is internally inconsistent. It's still skewed by our repulsion to sexual deviancy and our fear of being judged by our peers. We really can't distinguish right from wrong. We aren't even able to apply the simple test you proposed.