Richard Stallman is beyond any shadow of a doubt the Pat Robertson of the free and open source movements. He has consistently voiced opinions that are poisonous to a peaceful and cooperative relationship between commercial enterprise and open source development. Rather ironic since the biggest reason that his software ever got so popular was because many of its maintainers were hired by software development corporations. This, however, shows that the man has simply gone off the deep end and no longer even pretends to care about allowing others to make money:

Would it be ethical to steal lines of unfree code from companies like Microsoft and Oracle and use them to create a "free" version of that program?

It would not be unethical, but it would not really work, since if Oracle ever found out, it would be able to suppress the use of that free software. The reason for my conclusion is that making a program proprietary is wrong. To liberate the code, if it is possible, would not be theft, any more than freeing a slave is theft (which is what the slave owner would surely call it).

I really wish that were just being quoted out of context, but it isn't. The question is too blunt, and the answer too long and consistent from start to finish. After Wozniak got the transcript thrown right back at him over his assertion that he never said half of what he was alleged to have said, I'm not about to give Stallman the benefit of the doubt here.

The man really does have communist inclinations. He would freely steal that which does not belong to him, rather than convince the developer(s) to release it to him. I cannot respect a man, regardless of his accomplishments, who seriously says that the only reason he doesn't steal the work of others and appropriate it for his own work is that lawyers and men with guns (police) might take exception to that.

It should be worth noting that the most popular non-closed source software that is not the stuff written by the "free software movement," but rather the open source stuff like the Apache web server, PHP, Perl, the Jakarta tools, OpenOffice and Mozilla. Stallman is like the Canadian socialized healthcare purists who seriously believe that it is good that private healthcare is illegal in Canada. It really irks him that people can do stuff that doesn't jive with his vision for how things ought to be, even when they aren't infringing on his rights. In fact, this is one of the most amusing things about it all. Here's the netcraft analysis of www.gnu.org's web servers:

Apache/1.3.33 Debian GNU/Linux mod_python/2.7.10 Python/2.3.5

There are a lot of components that GNU created in there, but Linux, Python, mod_python and Apache most certainly are not GNU components.