Plyler vs Doe dealt only with educating illegals, but it was used as a precedent when the court overturned Proposition 187 in California, except it was extended to include everything in Prop 187.
Because GOP Guv Wilson was out going, it was up to incoming dem Guv Gray Davis to appeal and he didn't.
I agree with you Ben. However, as you said the proposition 187 case stopped at the level of the district court. It never got to the circuit court, and as a result there is no binding precedent on Montana. (Montana is in the 9th circuit, the same circuit as California, so if there had been an appeal to the federal circuit court it would have covered Montana).
In any case, even if there were binding precedent in the 9th circuit a state court could have held differently and the case would have gone to the US supreme Court. Also, arguably, since it was a different statute whose constitutionality was being considered and not proposition 187, even a federal court could have distinguished the other cases if the judges wishes to do so. That also would have brought the case to the Supreme Court.