If I were one of those engineers, and didn't believe in the claims being made, I'd personally be quite worried of being held personally liable if the company gets sued in the case of accidental death. Last thing I'd want is my bug being responsible for someone dying.
Good thing it would be almost impossible to attach personal liability to an employee of a corporation unless they intentionally designed the system to be unsafe with malicious intent.
E.g. I would quit too.