If that means that the CA IOU's are not bills of credit, I agree. But it would be false to say that states are free to emit bills of credit. If a state started issuing notes/money -outside of the federal banking system- they would be shot down, pronto.
Dense reading, but see Craig v. Missouri, 29 U.S. 410 (1830).
Easier reading, and additional case citations at, "Bills of Credit" from The Constitutional Law Of The United States, by Westel Woodbury Willoughby (1910).
As a State California could mint gold and silver as money. The California dollar could be one gram of Silver (31 grams to an ounce).