I remember the set of his shoulders and generally pained body language during that address. He knew it was bullshit, and knew that the world could tell that he was bullshitting. They sent him because out of the four (Bush, Cheney, Rumsfield, and Powell), he was the only one regarded as somewhat reliable.

He sold his soul that day and regretted it almost instantly. I agree that the people who put him up to it were also setting him up as they knew he already wasn't really with them on this thing. They were politicians, after all. I have no sympathy for the personal toll it took on him. He's a war criminal like the rest.