Well, I'm not sure that I would allow any conceivable t-shirt slogan in the schools ;)
My bad. By 'all the shirts' I meant 'all the shirts at issue in this matter', including the pro-civil-union signs and the 'Adam and Steve' shirts. I'm sure I could certainly dream up some T-shirt slogans I wouldn't want the school to permit.
...but I would certainly draw the line in such a way that this particular shirt, and expressions of opposing views, were permissible. It seems to me that these are students on the verge of joining the adult world - allowing them to gain an adult understanding of public discourse is certainly a worthy educational goal.
That's essentially my take on it as well -- it seems like an opportunity missed. If we're gonna make 'em go to public schools (and thereby make the First Amendment an issue), why not show them what the First Amendment is supposed to be for?
Well stated, but the problem is that education is not the primary goal of school administrators. School administrators are generally all cut from the same cloth - they tend to be petty tyrants, who prefer order above all else, and if forced to choose between order and education, they will choose order every single time.