True, but that is why there is a body of jurisprudence about what constitutes a true threat. It has not been settle by the SCOTUS, so various circuits have different applications as to whether a reasonable speaker, a reasonable hearer to whom the statement is addressed, or a reasonable person overhearing the statement would regard it as a threat.
For instance, if, in the middle of a pillowfight between two junior-high girls, one of the combattants is knocked down, and rises, still weilding only a pillow, and proclaims "I'll kill you," while grinning broadly and thrashing the other about the head and shoulders with the sack of down, no reasonable person in any of the various roles would regard the statement as actually threatening death. It would thus be protected speech under the First Amendment in any circuit.
It seems hard to see how a dream in a work of fiction could rise to the level of a true threat under any of the standards applied by the various Courts of Appeals.
The judges in this case affirmed a previous summary judgement in favor of the school. As I understand it, summary judgements are rare to begin with, because they're likely to be appealed. So judges will only grant summary judgement when there is no question as to the legal aspects of the case. The 11th Circus agreed.
I'm going to go with "there's more to the story than what's in this article." The courts clearly say a clear difference between the girl's story, and the pillow fight you described.