The level of pensions assumed they would stay in California, pay taxes in California and spend the money in California.
It may be necessary to impose certain requirements retroactively that pensioners verify that all of these things are done, otherwise reductions may be in order.
To the point, if they money stays in the system creating employment and is taxed, the impact doesn’t have to be as dramatic.
Where things go wrong and very badly, is when the money goes elsewhere, and taxes are not paid. But am I naive to assume that retired state workers all pay their taxes correctly to the penny.