I respect enormously where he's coming from, but he refuses to acknowledge the very simple fact that spoilers do occur, and in close-run races, they can change the outcome for the worse. He says the Democrats didn't understand the winner-takes-all Electoral College in 2000, while he himself dismisses his own part in that. Yes, ideally, Democrats would have played a better game and won by a larger margin and the spoiler wouldn't have mattered. But they didn't, and I think every factor that lead to Gore's loss should be looked at and criticised, including Nader's run.
The first and most important change that could be made in America is moving to a real voting system. First Past the Post is a sham. It isn't democracy. Whether the move is to IRV or MMP or STV or whatever almost doesn't matter. Just move to something real. Eliminate the spoiler effect, and then you can begin to see real meaningful policy change.