"I'm not stupid enough to have done that" might raise enough reasonable doubt to get you acquitted in a criminal case, although the prosecutor would probably argue that it's just as reasonable to think that you might have done it simply because you didn't think that a jury would find you dumb enough to have tried it. Depending on how good your lawyer was, you might or might not get away with it.
However, as I pointed out in the text you quoted, this is a civil case, not a criminal one. Just making the jury think that you might be too clever to have used your own IP for something like this won't work; you have to make them think that somebody else probably did it. My guess as a non-lawyer is that about the only way you can get the jury to agree with you is if you could demonstrate that you were on vacation when the download occurred, and that it had to be somebody else. (Note that if you can do this, you don't, as has been stated elsewhere in this thread, need to be able to say who actually downloaded it.)