an email address that nobody can access as he's no longer a part of that institution really isn't going to compromise much which is the problem he's now having as the school deleted it.
Typically though I would have to agree with you that emails should be hidden to protect oneself. In their case hiding it will change nothing.
When the day becomes the night and the sky becomes the sea, when the clock strikes heavy and there’s no time for tea; and in our darkest hour, before my final rhyme, she will come back home to Wonderland and turn back the hands of time.