I don't think you can take it that narrowly. They only moved the goalpost because it was an unopposed primary. Primaries are bounded by the party anyway, so it makes sense to give a single party the chance to run alternative candidates for the selection process.
I don't know that the court would have ruled the same way for the general election, since there are other qualified candidates on the ballot. It wouldn't be a case of limiting the choice to one as it would be in the primary, which is by definition a narrowing process.
Just my opinion.
-PJ
This will be the case the dems rely on. Whether it will stand the test of a higher court is definitely uncertain.