The Supreme Court's opinion didn't "throw out the case", or say that the guy goes free, or that what he did was OK. The Supreme Court's opinion just said that the prosecution did not meet the level of proof required by the law (specifically, the question revolved around whether it's enough to just show that the statement was interpreted by someone else as a threat, or whether it's also necessary to show the statement was intended as a threat by the person who made it). The prosecutors are free to hold a new trial and try to meet the higher level of proof.
Most legal scholars who I've read on this seem to think it is trivially easy to meet that higher level of proof, and so it won't make convictions for threats much harder to obtain.
