> Maybe you could point to me where 37Signals no longer has what was stolen?

I'm in full agreement that copyright infringement is not theft.

However, I think this part of the argument is weaker. Things can have value through scarcity, and even more so through uniqueness. To copy something, in such cases, can lead to a reduction in value of the original. If what you had was "the only <whatever> in the world" someone copying it takes that away from you without ever taking the item away.

Whether that's true in this specific case, is a somewhat different argument, of course.