This isn't about mean or nice. He broke the rules and management will have to figure out if there is a consequence or not. Neither you, nor we, can decide what approach to policy is right for this company.
Edit: Oh, and email accounts may be preserved to retain the information they contain. If I were to leave my current company, they would need to keep my email account open so that they would still have the records of the work I've done. The onus is on me to have integrity, if I fail that then I don't deserve anything given in a severance agreement that I've broken with my own actions.
So? Preserving the account doesn't mean that the ex-employee still has access to it. My account at my former employer is still open, but I can't access it. My former boss has the passwords and I don't know what they were changed to. If you (generic) lay someone off (or fire them, terminate them, RIF them, "let them go", or "encourage them to seek new opportunities" -- how many angels can dance on the head of that particular pin?) and you don't immediately change their passwords and other access data, then you are a fool. Even the nicest people can do bad things and if a company actually wants to protect themselves, they have to take positive steps to do so.
This. Exactly. I can tell you right now that where I work, the minute you are no longer employed, for whatever reason, IT is informed and all your accounts, including email, access to share drives, ability to connect from outside computers, etc., are terminated. Again, as artk pointed out, that doesn't mean they disappear. Not by a long shot. Just means the former employee no longer has access. If the company your brother works for doesn't have a process in place to handle this, they are asking for trouble and sooner or later, someone is going to mess things up a lot worse than just sending emails for references.
I also agree that someone's personal life should not enter into consideration of how good an employee thay are or whether to lay them off or not or whether to bend the rules or not. It smacks of the old "men have a family to support and women don't" philosophy for paying men more than women. Employment, compensation and expectations should all depend on employee performance and nothing else.
ETA: I'm not sure how this relates to etiquette, though. More like a discussion about business practices.