The Pirate Bay Trial - A Spectrial

I think you are misrepresenting the logic. The difference here is the difference between a common sense argument & an argument that contains clearly distinguishable definitions. The latter is the kind needed (usually) for legal matters. But a lot of the time we are just trying to find a legally acceptable definition for the common sense argument. 'Illegal if it's mostly for illegal stuff,' is not the kind of law courts would be comfortable with. But I would argue that the issue is with defining an abstract principle. Sometimes these issues are resolved with linguistically.

The Pirate Bay's Raison D'Etre is pretty much to do with illegal content. The existence of some legal reasons is a fringe issue. (You might dispute this. In that case, the argument is over this point.) Imagine your unlocked bike list. Or how about a children home alone list. Defining this in an airtight manner that would satisfy the common sense is almost impossible. Specifically defining 'mostly' (as in mostly illegal content) would create a situation where there is a threshold to be met. This shelter could be used as a shield against prosecution. Defining it in terms (eg intent) would create different problems.

But these are problems always present in legislation. That doesn't mean you give up on laws. I think that most proponents of Pirate Bay (regardless how clever the arguments) are in the medical marijuana camp. They aren't themselves convinced that Pirate Bay should be there because of possible legal uses. They are themselves convinced by believing that content should be free or that IP laws should be changed or that Government shouldn't take on itself the role of policing this realm.

I don't know about Sweden or Denmark, but anyway I suggest not to jump to conclusions unless you know more about the laws in those countries.