I do think he's a bit manic and probably too unpredictable to take on a job that is so far removed from his media "career". Let's face it, it's hardly likely to happen.
But I agree with a lot (though not all) of the things he says. He has dared to deviate from the "austerity script" that the majority of our politicians and commentators so slavishly follow. The backlash from that has already started, as paper after paper have slated him and his book today. Perhaps he's too naïve to have suspected that would happen.
Time will tell if he is genuinely committed to social justice or if it's all just a passing fad. I did hear him say he would be putting the proceeds of sale of his new book towards some sort of training initiative for young people - it will be interesting to see if that materialises.