Interesting link. I found the OP's lack of comment interesting, as was the organization's need to defend against a novel. If the insults are baseless then legal action might be more appropriate, certainly less attractive.
Or perhaps they follow this teaching:
"Blessed are you when people insult you, persecute you and falsely say all kinds of evil against you because of me. Rejoice and be glad, because great is your reward in heaven, for in the same way they persecuted the prophets who were before you. (Matt. 5:12. ASV)