The regulation requires that you disclose "any minimum balance" to obtain the APY, and says that all disclosures are to be made "as applicable." That means "if it don't apply, you needn't supply."
Since there is no minimum balance to earn the APY, you do not need to disclose one, IMHO. But the $0 amount disclosure is not a problem.
John S. Burnett
Fighting for Compliance since 1976
Bankers' Threads User #8