He dowsn't have a choice really. If he says everything is my fault I suck as a GM he will get fired. That may be what we want but that certainly isn't what he wants. If he says I did everything right, stuff that happened is all out of my control and I would do the same things given the opportunity. He would still get fired but this time for beeing delusional and selfish.

What can he do then? Just like he did take the blame in general but still blame other things when it comes down to specifics. It's not fun for us because it's not logical but having fucked things up like he did I would say the same bullshit : "I fucked everything up, I'm sorry, it's not my fault. We'll bounce back. "