If you build something you should definitely have something to say about what others can do with your work, especially if you give it away for free. And nobody imposes something on you - you are perfectly free not to use GNU licensed things.
I don't recall arguing otherwise. But compared to the BSD license, it's definitely more restrictive about derivative works. Also, the slavery analogy is stupid.
I think it would be helpful to be clearer as to why you disagree with the analogy rather than simply calling it stupid.
If I had to guess, I would suspect that your real issue is that you do not find the things being restricted to be comparable (i.e., human life/will vs. the use of software), rather than believing that the comparison is somehow invalid for other reasons.
First of all, it's not a good analogy. Software licenses are a contract that you can choose to agree to, whereas laws give you no choice.
Second of all, it is highly debated wheter the restrictions imposed by the GPL are a worthwhile tradeoff; while noone in their right mind claims anybody has a right to own slaves...
And lastly, by comparing the GPL to laws against slavery you are trying to evoke certain associations, much like stallman uses the word swindle instead of kindle -- those are just cheap tricks that distract and make fruitful discussions hard.
