Etiquette firmly opposes both obscene and malicious talk, but this does not imply that speech needs to be restricted by law. Etiquette does not necessarily even oppose the expression of offensive ideas. Rather, it dictates that there are situations in which the expression of potentially offensive, disturbing, or controversial ideas is inappropriate and that, where appropriate, the expression and discussion of such ideas is to be done in a civil manner.
The judgment that 'the journalists at a news conference should not ask a politician potentially embarrassing questions about a controversial policy issue' most closely corresponds to the principles of etiquette stated above.