The outsider test is kind of like an onion. On the outer layer, there is a legitimate appeal to be fair to opposing views, to counteract bias, etc. At that level it operates as a kind of golden rule for beliefs. So it is sometimes helpful to imagine yourself as an outsider to your religion, treating it with the same kind of skepticism with which you treat other religion.
But if it is restricted to religions, then people who are not within a religion get an automatic pass, since it isn't hard for an atheist to say he is just as skeptical of Christianity as of Islam, since he believes both to be false and delusional. Should atheism get a free pass here? I know a lot of Christians who work very hard at coming to terms with the "inconvenient truths" for the Christian belief system. If you go to a Society of Christian Philosophers meeting, the best-attended session is always the session on the problem of evil. And then I see atheists treating their own view like a slam-dunk, as if there are no inconvenient truths for their world-view. You get the argument that their position is different because it is a non-belief, rather like not collecting stamps. You get the argument that allegiance to science somehow gives them a free pass. It is like pulling teeth to get some people to realize that confirmation bias doesn't stop once you go out the church door and shake the dust off your feet.
And, you get the argument that we can judge who has "really" taken the outsider test, based on whether the one claiming to take the test has reached the same conclusions about religion that the atheist has reached. They say, "This is the conclusion I have reached, I consider it to be true, so if someone comes to an opposing position, it MUST be because of insider bias, of a failure to REALLY take the outsider test." This in the area of biblical scholarship, where there is little consensus, and a lot of presuppositional issues to deal with as well as evidential issues. Here Tim McGrew's distinction between the heuristic and diagnostic uses of the outsider test is important. It isn't the test I object to as the way it ends up being construed, and the idea that atheists can look at their own answer key to test whether someone has really taken the test or not.
I have never seen an overall superiority of atheists to theists in the area of maintaining that constant struggle to come to terms with the inconvenient truths for their own philosophies. If anything, it has always looked to be to be the other way around.
I realize this is not really an answer to the specifics of Arizona Atheists's response to me. I will get to that, I hope, in the next day or two.