The answer to your question in two words: Contract LawMy thoughts are with Frank. His seem to be more accurate and sound more believable. If the state were to re-vamp the safety employee pensions to bail them out of THEIR mess, what's stopping THEM from coming after the employees with existing benefits? California politicians know that CALPERS is the strongest retirement system with the most money and that's why I'm voting to throw out all current incumbents with my vote against!
The CHP voluntarily entered into re-negotiation of their existing labor contract. That is the difference.
The only way for a governmental entity to abrogate a contract is to go into virtual bankruptcy under current state law for governmental units. This is not the same as you or I declaring bankruptcy and I am not certain any state has ever defaulted in its contracted obligations. Municipalities in California have defaulted and labor contracts were re-negotiated under court supervision.