Supreme Court doesn't issue advisory opinions.
Wikipedia on Declaratory Judgement
"A declaratory judgment is typically requested when a party is threatened with a lawsuit but the lawsuit has not yet been filed;"
Too late for Cruz now. The lawsuit has been filed.
Who can be sure the courts would even render the correct verdict? Apparently written words in the law aren’t enough to take at face value. People get hung up on intent, which is like detecting micro aggressions in spoken words.