Ian left the USA, apparently over concerns regarding the status of civil liberties. This is not some mere flame war, but an individual who has taken a drastic step. To call Ian's claims about 1930's Germany a "red herring" is to trivialize Ian's actions.
If one calls Bush or Ashcroft a "Nazi" in some blog posting about some outrage or another, but does little else, that is most likely an example of Godwin's Law. However, to actually act on that position and leave the country (as one should have either fought the Nazis or left Germany) is not an example of Godwin's Law. Either Ian's drastic action (and implicit call to action by others) is justified in the current climate or it is not.
After all, if the civil liberties climate is such that it is a justified action to flee the USA and seek refuge in Europe, then we should take the issue quite seriously. It is one thing to talk about "Nazi Germany" in the context of file-sharing or filtering, it is another to speak of it in the context of people leaving the country because of fears regarding civil liberties.
Doctorow is wrong. This isn't a red herring, but the crux of the matter.
On the other hand, perhaps Ian's actions should be trivialized.