While I realize that in certain cases such as solicitation of murder, one can and should be held accountable for influencing another to commit a criminal act, even to the extent of saying that the influencer is not only as guilty but in some cases even more guilty than the one who committed the actual violence, it is different in this particular case and in the case of suicide in general.
With regard to your disticntion of moral and legal culpabilty, I can only agree that in cases that relate to suicide as a result of negative behavior toward that person, the culpability only goes as far as what that negative behavior actually was.
In one of the examples I listed where I would have had a bad day then treated someone in the manner of a jerk, and then that person later committed suicide, I am morally culpable of behaving as a jerk.
It is possible that I would make the connection in my mind that my jerkish behavior may have been a factor in this person’s decision to commit suicide, or it may not have been. In either case, the only thing I am guilty of is behaving as a jerk.
Notice that in the case of Dharun Ravi, he was found guilty and sentenced only on the crimes that he actually committed. He was in no way guilty of causing this man’s death. Clementi caused his own death. I beleive Ravi did behave as a “jerk” and criminally so, in so far as he invaded privacy and did intimidate or humiliate by posting the video online, but if I recall correctly, people wanted this man to do hard time for this event, which would have been a miscarriage of justice.
And I would simply refer back to that, "Do unto others," prescription which might have prevented the suicide, and would have entirely eliminated any moral culpability :-)