I think the "encouraging someone to take a non-criminal action" angle is weakened in cases like this: the person is obviously mentally ill and not able to make good decisions. "Obvious" is important, it has to be clear to an average adult that the other person is either ill or skillfully feigning illness. Since any rational adult knows the danger of encouraging suicidal ideation in a suicidal person, manslaughter is quite plausible in certain cases. Again: if this ChatGPT transcript was a human adult DMing someone they knew to be a child, I would want that adult arrested for murder, and let their defense argue it was merely voluntary manslaughter.