> If a bank's SWIFT credentials are compromised the attackers can transfer all the funds a bank controls. With a blockchain coin it would require the private key of the customer to send the coins.
Replace "SWIFT credentials" with "private key" and you have exactly the same scenario.
> You know if you're going to be wrong you should be less vociferous about it
Needless petty snark.
> Compromising SWIFT credentials allows you to send money from any account. Compromising a customer's private key would only allow you to send money that's in that one account.
If the "customers" are "banks" as you stated, then there is a 1:1 relationship between SWIFT credentials and private keys which allow one to sign transactions on behalf of the "customer" (bank).
There are no "customers", this is a private blockchain where only banks participate.