The question is how obvious is the causation between posting pictures of Clementi having sex on the Internet and his suicide. If someone asked me if its reasonable to assume someone may commit suicide if someone publicly humiliated them in that way, I'd probably say yes.
On the other hand, the kids pulling the prank, while mean-spirited, are still immature. Did they really think they were doing anything other than pulling a prank? Did they think through the consequences? That is a mitigating factor.
I don’t know if wrongful death or involuntary manslaughter would stand as a matter of law or with a jury. But these kids did commit a felony. They did not consider any possible consequences other than their thrill and maybe Clementi’s shame. Nevertheless, someone died at least indirectly from their commission of a crime. Therefore, they are not entitled to any mercy or mitigation of the punishment for the crime they did commit.
If 5 years is the maximum penalty for the crime they did commit, I would have no problem if the evidence is as presented with giving them the full punishment under the law. Most drunk drivers do not intend to kill anyone. Nevertheless, people are killed and the drunk drivers go to prison for a very long time.