I think I understand the point of view of those opposed to sopa. However I also think a balance needs to be struck between safeguarding liberty and freedom of expression on the one hand and protecting people's property on the other. The advent of the internet has made copyright much more difficult to enforce than was previously the case. I think one has to make the default assumption that if one posts their deepest thoughts on the internet, they effectively become public property.
A few years ago I posted a pee desperation story on an adult website and was subsequently delighted to find it published some months later, without any acknowledgement, in a magazine. I complained to the magazine in question only to be told rather bluntly that as I'd posted it on their website it was theirs to do what they wanted with and, if I'd read the small print on the website I should have been aware of that. Legally I don't think they had right on their side - at least not under UK law. However they also realised there was little realistic prospect of me taking them to court over it and gambled, quite correctly, that they could get away with it. However that didn't make it right morally or, I suspect, legally either.