The person should be able to accept any insult and embarrassment he is going to receive for his actions. The way you treated others are exactly the same way you are going to be treated..There are some people who actually find it very difficult to forget how you treated them bad when you were their boss. If this kind of person happens to behave that way, there is no way he or she is not going to pay back whatever you did to them when you were their boss.
I can understand the part where you are talking about the person having to go through humiliation and depression of having to become a worker for someone who used to be his own staff.