"Censorship is the suppression of speech or other public communication which may be considered objectionable, harmful, sensitive, or inconvenient to the general body of people as determined by a government, media outlet, or other controlling body." - http://en.wikipedia.org/wiki/Censorship
This is so that depending on what audience you have writen for you do not offened anyone who reades the script or waches after it is produced.
Writers have to make sure that if they base a character on a real person that they do not insult the person, they have to make sure that they do not falsely accuse them of something.
"If you write libellously about a person, basing a fictional character on someone known to you, you should not think that changing the person’s name will protect you from being sued for libel. If anyone can recognise the portrait you have painted as being that of the person concerned, however disguised, you still risk a suit for libel."
The site also says about how if you insult a person that it can be quite bad but it also says that if you do that and them comment about the perfeshional work that it would be even worse, then the person that the writes has made theas comments about coudl easily be taken to cort.