The certificate is a contract. Any ability to suspend paying interest because the bank concludes the contract is void due to the death of the account owner is a matter of state law and I would direct this question to legal counsel.
From a reputation risk perspective, if counsel says it is permissible to hold the beneficiary's money interest free, consider their reaction when they find out as well as all their social media friends' reactions.
_________________________
Sola Gratia, Sola Fides, Sola Scriptura, Solus Christus, Soli Deo Gloria!
www.tcaregs.com