Why should politeness, courtesy, and intelligent discourse be considered and "ideal" instead of the "normal" way to discuss an issue? I've met Aussies who are well able to control their language and can carry on a conversation without offensive behavior.
It's the rude and ignorant among us who seem to want to impose their own offensive behavior on others rather than the other way around. One thing is certain, a "Spaceman" or "Ensign" will certainly want to choose their own words more carefully when confronting an alien race.