The analogy is that non-free software is akin to censorship. Free speech for everybody is the ideal, in reality we have yet to achieve that (see for example Chi

The analogy is that non-free software is akin to censorship. Free speech for everybody is the ideal, in reality we have yet to achieve that (see for example China), and approving of censorship is a step backwards. Free software for everyone is the ideal, we have not reached that goal, and approving of non-free software hinders progress.