On reflection, it seems an odd manner of quarantining politics from other aspects of life. And taken to the logical extreme (if artists should stay out of politics, should bakers and plumbers, too?), it essentially means that politics should be left to the politicians. Which, to me, seems a particularly dangerous proposition.
In a participatory democracy, politics is everybody's business. This is true in other parts of the world, where political discussion is as common as sports chat is here in America. The only way to keep our political arena healthy and honest is if every one of us pays attention, says what she thinks, and joins in the bloody fray. Blogging is showing itself to be a great method for this. If you disagree with my political view, you can comment on my post, and maybe I'll end up being convinced. How do I know if we don't open the discussion?
True, as Stephenson (whose writing I quite like) points out, I could easily make a fool of myself by exposing my political views, but I risk making a fool of myself every time I lay my fingers on a keyboard. If I fear looking foolish, I'll never write a word.
As for his last reason for avoiding politics:
A novelist needs to be able to see the world through the eyes of just about anyone, including people who have this or that set of views on religion, politics, etc. By espousing one strong political view a novelist loses the power to do this.
I wasn't under the impression, Mr. Stephenson, that your imagination was so limited! Surely you are capable of saying "murder is wrong," and yet portraying a murderer with compelling empathy.
I can understand a wish to deflect readers from assuming particular political bent in his work, and it is his prerogative to do so. But I reserve the right, respectfully, to disagree with his blanket statement, and dive into the nasty fray, teeth sharpened.