If the state is unable to pay, then that's not a reason to renege on only these payments - just as in the "robust bankruptcy court for individuals" doesn't mean that you get to skip that one bill that you dislike while all your other assets and creditors are untouched, also if the state of California goes bankrupt, then all outstanding debts are in it together instead of removing pensions while paying other bills in full. The state has a budget surplus, it better start saving it up to pay its future bills.

The fact that their obligations are unfunded is a major problem and borderline accounting fraud - they should start treating it as actual debt, even if suddenly noticing the elephant in the room would actually invoke talks of bankruptcy. Coincidentally, this would also mean that the voters can implement the required changes for future, no matter how scary the wording on the bill sounds.