I think there's definitely an anti-Islam bias, and it's not too difficult to understand why. New Atheism tends to run with a very uncritical Enlightenment core, and modern Christianity, at least in the West, tends to be much more open to secularization- it's much more "toothless" than Islam to some extent. The combination of those two things make room for that kind of bias. Obviously, the reasons for this are historical and geopolitical, since there was also a time when Islam was much more secular and and progressive, while Christians were not.