The way I consider it quite similar is that the freedom to own slaves isn't a real freedom, neither is the freedom to use my code to restrict other people's freedom in computing.

Can't you just accept that other people are honestly seeing something that you're (not seeing/see but don't agree with) rather than accusing people who disagree with you on this of being cynically dishonest?

Are drivers licenses also a form of slavery because you're not allowed to drive with out one, and in order to keep it you have to follow most of the rules of the road?

Most people would say that it's ridiculous to compare drivers licenses to slavery, even libertarians will tell you it's a loss of freedom but few would compare it to slavery, because for the most part drivers licenses and slavery have nothing in common.

Slavery is discussed in political philosophy all the time, even in "Anarchy, State, and Utopia" by Nozik (with which I happen to disagree, but that's nor here nor there). I did not read the first message as an hyperbole, but simply as a consequence of the fact that "enjoying freedoms while preventing others from enjoying them" brings slavery to mind quite often. It's an unfortunate, possibly unnecessary metaphor, but not necessarily a piece of rhetoric (although, like everything under the sun, it surely has been used to that effect as well).