The original article talks about legislating against certain capabilities (software) of general use computers that allow the commission of illegal acts.
The chain of metaphors has gotten pretty stretched. As far as I can tell it goes about like this:
Author supports SOPA and criticizes Google for allowing people to find copyright content to steal.
Commenter doesn't like this so quotes Doctorow talking about wheels to explain why we shouldn't make running websites or search engines illegal or restrict their capabilities.
You point out that we do restrict the use of cars.
(Thus by metaphorical extension seemingly supporting the idea we should restrict using search engines or websites for illegal acts)
I point out that you are talking about restricting the use of cars, not restricting their capabilities.
(Trying to point out by metaphor the distinction between restricting legal use of search engines and legal capability of search engines)
You say we agree, but quote what I considered to be the obvious and not important part of my comment. (I thought the important part was: "What we shouldn't (generally) do is preemptively prevent your from having the ability to commit that crime, especially when that prevents you from performing activities that are not crimes.")
Assuming that we don't agree on the crucial point, I go further off topic and bring up another unrelated example of ways people are restricting the capability of computers (by making it illegal to export extrusion software.)
So let me see if we do agree explicitly on the original topic:
Do you support SOPA? Do you think that we should make it illegal to index and share links to websites of people who break the law (e.g. distribute copyrighted material or share intrusion software)? Do you think we should make it illegal to provide others the capability to break the law even if we are not breaking any other law ourselves?
...Or did we just get really lost in our metaphors?