How can he "refuse to do so?" If someone tells you that you are no longer employed, and to leave the building one cannot simply ignore it and continue working. Similarly, one cannot ignore commands or sanctions from a workplace superior if one hopes to remain employed. This is not simply the intern's problem. People are not allowed to work in inhumane conditions, whether they would choose to or not. People cannot sell themselves into slavery, even if they want to. Just as employees have responsibilities to their employers, the reverse is also true. A major part of those requirements is maintaining a safe, healthy working environment. This represents gross negligence on the part of the bank.