I think I agree, for the most part. I have no problem with people arguing that copyright shouldn't be called theft, but I do have a problem with people arguing that copyright can't be called theft.

Perhaps the distinction is finer than the subject deserves. If I'm honest I think I prefer the "should not" argument to the "may not" one because the latter begs for shallow, deductive arguments from definitions instead of admitting a more thoughtful discussion.