For what it's worth, I think the court almost had to do this. As a technical matter, they haven't sent the case anywhere: what they've done is certified a question of California law to the proper authority on California law. My own read of the order suggests to me that they pretty much had to do this, because (a) it isn't clear that standing exists under California law; and (b) it's pretty clear that it wouldn't if the panel follows the usual federal rule. That is, I'm reading the order as saying to the California Supreme Court, 'We're going to have to toss this unless you tell us there would be standing under state law, and throwing the case out strikes us as making kind of a mockery of your bizarro-land voter-initiative process.'

The stakes are just too high for them to make their own finding as to California law on the point, as they would be entitled to do and would probably do under any less fraught circumstances. Neither throwing the case out nor letting it go forward when the issue of standing is this difficult is really a good option; no matter what, it would give the losing side a weapon with which to attack the result for all eternity.