This is an old trick, and the Dems seem to get away with it.
You can bet that the budget cuts do not need to come mostly from government schools; however they are visible and perceived needs. Low info voters will read this and react in fear that the little kiddos will suffer. (And, Moms and Dads at home will similarly react in fear that if schools are cut, then THEY will have to work from home w the kiddos, and can't go back to work).
There is a multitude of other choices, but Mister Newsom chooses to try, one suspects, to justify begging for fed $ or increase taxes by fake threats to his own school system.
One note: The Cali public school system could do with a comprehensive audit and a major cut in funding that does not affect education. That is an important, however separate issue.