Any deviation from policy can get a manager fired.
To withdraw funds you must be an authorized signer on the account. To accept verbal instructions over the phone would generally need to be preset - i.e. agreement signed and on file. Unless the employee sent to the Bank was already an authorized account signer I do not see any bank manager putting their job on the line.
If everything was preset. Authorized signer on the account used by SS present, or previously listed as authorized to withdraw. It could work, but would still be hard to pull off in such a short time unless set up at minimum the night before - probably longer. Banks really do not keep wads of $100 bills around. They look at patterns and order weekly cash based on those patterns. They would not risk giving away money they might need to cash payroll checks on Friday. And yes, a large sum being withdrawn would require additional paperwork as others have mentioned. The Bank would typically escort client to a private area to count the funds together and put money in envelope - for security and also to avoid claims of any bundle being "short". This too would eat up some time and require a staff member be available. Banks are thrifty and usually keep bare bones staff at branches - according to normal traffic patterns.
Safe Deposit box - highly unlikely as there really is one key and multiple steps to identify who has access to that box. Not to mention its frowned upon and poor business sense to keep cash in boxes.
AIW may have had a safe with cash, but $40K seems like a lot of petty cash and its NOT the story provided by the W1 witnesses.
Last if this was not preset and it occurred at the Bank - red flags would have gone off. While at the Bank we called the police many times on odd events or suspicious transactions and had people arrested while waiting for us to "confirm data". My own staff stopped an elderly lady from giving her savings to a con man, a junkie from scamming an elderly man, and alerted a company that an employee might be embezzling via credit card overpayments. Bank staff are generally alert.
