The principle of the guy being able to insult me to my face and he gets immunity? Fact is that the marshall of the parade should not allow such stuff. Once upon a time, he would not, but now atheists and gays are thought to have the right to ridicule the religion of other peoples.
The principle of not having your person violated by a stranger. Do you not see that the Muslim attempting a strangulation on the person in question was a violation of his rights?
That said, who ever guaranteed you immunity against insult? Anyone should be free to insult anyone else. Otherwise, the freedom of expression has no meaning.