I don't understand his point at all and suspect that he is not an atheist, but instead uses the cause of atheism to puff himself up and mock others.
P Z Myers is a scientist by training. He blogs a lot about evolution and clearly understands quite a bit about physics and biology. He also has a good command of logical reasoning. As an atheist and a scientist, he must understand cause and effect, particularly as it applies to the chemicals and chemical reactions that make up our existence. If he really was an atheist, he would believe that we have no souls that drive our decisions and that our decisions are simply the result of chemical reactions and the absorption and release of energy.
In short, P Z Myers' reactions lack the peace of mind that comes with true atheism, the realization that nothing has meaning, that things happen because that's what they do. The religious people he mocks and the objects he longs to desecrate, are not the villains he wants them to be. Just like him, they are simply the current form of those packets of energy and those subatomic particles. The Catholics who became enraged at the desecration of the host did so because that's what those subatomic particles' existences led them to do. His entire objection to religion and those who practice it, his desire to desecrate the body of Christ has no meaning at all.
P Z Myers' most notable characteristic is not his atheism. No atheist with the training and the deductive powers that he clearly possesses would bother with such actions. I doubt that he has any real underlying philosophy at all and instead has a particularly strong, childish need for attention. That he chooses atheism as his vehicle seems arbitrary. He is the intellectual equivalent of a flasher.