Polonius, Hamlet, and Privacy

I believed that snooping is a bad idea becasue it is not OK to invaded the privacy of another person. It is bad because no one like being snooped on. Why did they do it in Hamlet life? It is simple, they are trying to get hamlet life style out and his privacy out too, after his father death. Hamlet trys to be calm after his father death because he want it to past, or he want to make a payback plan to the murder who kill is father when he is asleep.