Think of it this way...
Do you want the players of SL to have the power of the word, Bastard? The 13 year olds? 14? 15? 16? And on?
I, personally, would not like to see "Bastard" in every sentence of the game. Whether you believe it or not, it will happen.
If anything, since the game is "children friendly" the events in question should be re-worded.
Never-the-less, Naruto (Both the Manga and Japanese Anime) uses the word Bastard.
They also utilize many other words that most deem as inappropriate.
This is why the Naruto Anime (English Version) has been edited to not include these words and instances.