With regard to Durie I think we've reached consensus to keep it out.

With regard to Breivik - it's a reliable high quality source, it directly supports the text that is being included, it is obviously notable (the fact that breivik used the term and how he used it), and it is relevant. So I really don't see any reason for removal except some kind of WP:IDON'TLIKEIT

With regard to the side bar - the underlying problem is that the very subject of this article, "Dhimmitude" is a POV-loaded term itself, usually used by people with a particular ideology. Part of that ideology/POV is the view that Muslims always and everywhere discriminate against non-Muslims and that this discrimination is captured by this term. But once again - this is just a POV of a particular ideology. If this sidebar was text we could properly attribute it (so and so says that Dhimmitude reflects discrimination etc.) But with a sidebar we cannot do this. Since we cannot properly attribute a sidebar the only recourse is simply to remove it. This is the same as if someone tried to put an "Apartheid" side bar in the article on Israel or something - it'd be POV, just like it is here. In fact, given the generally fringe usage of the term, by fringe folks, an "Islamophobia" sidebark would make a ton more sense than the "Discrimination side bar".