I am familiar with the meaning of blank check as in carte blanche. Receiving a blank check, in this context, is quite a good thing for the recipient (though perhaps not for the issuer).
In a recent article, however, I encountered a negative connotation to receiving a blank check:
Attorney S. Lee Merritt said the family has not been satisfied with the information coming out of the district attorney's office. Nor were they pleased it took three days to charge Guyger when, in Merritt's view, the officer's admission she shot him was sufficient to merit an arrest on manslaughter charges, he said.
"The promise of transparency to this family has been a blank check," Merritt said.
What is meant in this context? Is this a regionalism, or perhaps a hyper-correction?