Thanks, the circumstances around the debit account that was closed is the probable issue. Their terms and conditions have vague language so that they can apply to very broad circumstances.
>>I. Bank’s Right to Suspend or Terminate your Use of the Services.
We reserve the right to limit, suspend, or terminate your use of the Services or take other account-level or transaction-level actions, as well as suspending or closing your Apple Cash Account, immediately and without prior notice to you for any reason, including, without limitation: (i) to protect the security and integrity of the Services, your Apple Cash Account or Apple Cash Balance, or other Users and their accounts; (ii) the inability to debit or collect funds from any account you designate in connection with the Services; (iii) if you breach these Terms or any other agreement with us regarding the Services, including, without limitation, by using the Services for any unlawful purposes; (iv) we have reason to believe there has been or may be an unauthorized use of your Apple Cash Account; (v) we are unable to verify your identity or authority to use the Services to our satisfaction; (vi) your Apple Cash Account is not in good standing; (vii) we believe that your use of the Services could expose us, Apple, or other persons involved in providing the Services to increased risk or be placed in a false or derogatory light; (viii) your Apple ID is suspended or terminated for any reason or ceases to be in good standing with Apple; (ix) we have reason to believe that you are using the Services to facilitate, encourage, or promote illegal activity, hate, violence, intolerance, fraud, or otherwise objectionable content or activities; or (x) we believe your use of the Services does not comply with applicable law. Our election to exercise the foregoing right to suspend or terminate your access to and use of the Services is in addition to any other right or remedy that we may have under these Terms or otherwise. Our decisions may be based on confidential criteria that are essential to our operation of the Services, management of risk, and protection of Bank and other Users. We may use proprietary fraud and risk modeling when assessing the risk associated with your use of the Services. You understand and agree that such action is reasonable for us to take in order to protect us from loss and ensure the security of the Services. We reserve the right in our sole discretion to grant or deny reinstatement of your use of the Services.<<
In other words, banks are private businesses and choose who are their customers. If the account holders activities expose the bank to potential losses, or other risks, they can cancel an account. This sounds unfair, I know, but banks have been under much heavier scrutiny since the banking crisis of 2008 and 9/11. Banks face heavy fines for the activities they permit customers to do, if they are in violation of banking laws and regulations.
Typically banks will only talk to the account holder. This could be the reason for the lack of information. Another possibility is the Patriot Act which was enacted after 9/11. The act strengthened the Bank Secrecy Act and anti money laundering laws. Your son may not have been engaging in money laundering, but banks will permanently lock and close accounts that engage in suspicious activities. Even if anything resembles fraudulent activity or money laundering it will get an account permanently locked. This could be the issue surrounding the closed account you mentioned.
At this point if you're intent on pursuing getting the account opened, your only recourse is the CFPB (Consumer Financial Protection Bureau). They’ll at least pursue the complaint and Green Dot will be in touch concerning the account. Beyond that, there’s unlikely to be anything else to pursue.
https://www.consumerfinance.gov/complaint/
https://applecash.greendot.com/termsconditions/