The Baraboo (Wisconsin) School District has so decided, contending that it "cannot know the intentions in the hearts of those who were involved" and that any proposed discipline would violate the First Amendment.
I don't want to get into the merits of either these justifications. Hearts are notoriously hard to read (itself a good reason not to hinge our approach to discrimination on the fickle organ), and I'd have to do more research to feel confident appraising the merits of the First Amendment question (on the one hand, presumably the school's power is limited in cases of off-campus speech like this, on the other hand, remember "Bong Hits for Jesus"?).
All I want to say now is something I've said before: They would say it about Jews; they'd say it about others too. Sometimes one hears claims to the effect that "nobody would ever tolerate such-and-such behavior if it was targeting Jews", as a claimed contrast to cases where social actors are tolerating some form of bigoted behavior which targets another group. It's an ugly bit of victim-competition which attempts to cast Jews as having yet more unearned privileges and advantages that set them apart from the truly marginalized.
But, as we see here, people do target Jews with hateful acts, and other people do let them get away with it. The myth that -- alone amongst the oppressions -- any hostile act towards Jews (and -- the implication often goes -- many acts that aren't really hostile at all) is met with immediate and overwhelming punitive firepower is just that: a myth. It isn't reflected in reality, and it shouldn't be relied upon.