I am opposed to copyright and patents overall. However, I do think that copyleft is a relatively appropriate way of reversing the damage that copyright does. It's not perfect, but it's a legal hack. It's taking poison and turning it in to an antidote, and in that regard, it's an incredible piece of work. My views are not identical to Stallman's, and while I agree with him on a number of subjects, I disagree with him on others.
If you are, like me, a copyright abolitionist, then, at least from our perspective, it would be just to ignore all copyright law, which would include violating the GPL. If you are doing much of anything other than asserting a new copyright on a GPL'd work (thus, selectively ignoring copyright law without a consistent basis) and aren't a billion dollar company, it probably isn't even worth it for the SFLC to bother you about your non-compliance. And if you are ideologically self-consistent, you would be ignoring lots of non-free licenses as well.
You seem to be interpreting my stance from the perspective that copyleft is unjust while the remainder of copyright is just. I've yet to see an even slightly cohesive consistent argument to back that viewpoint. There are many that hold that position, but none of them present decent points.