David Mitchell is one of many people I've seen that misunderstand the definitions of 'agnosticism' and 'atheism'. He says that agnosticism is the most rational position is as though it's a mid point between theism and atheism, when in fact anybody who does not completely accept theistic claims is an atheist ("I'm not convinced there's something").
"I'm not ready not reject it" makes it sound like atheism is claiming no God exists, which not the case. You can choose not to believe 'X' without saying anything about 'Y'.
His take on things seems a bit too influenced by his own advocacy that he hopes something exits. There's nothing wrong with hoping something exists, but it seems to completely drift off from the difference between agnosticism and atheism.