should provide the potential user reasoning for why they are denying him access.
Why? It's common that companies can deny service to anyone for any reason and they don't have to tell you why. For example, see the ToS of Fold themselves:
3. Access to the Services
Fold retains the right, at our sole discretion, to deny service or use of the Services or an account to anyone at any time and for any reason.
I know it sucks as a customer but from their perspective, it's reasonable.