It's not a legal defense strategy, it's a social engineering strategy

If nobody brings forward a lawsuit in the first place, why would there be a judge?

The judge doesn't accept it, and the Wikipedia page points out that this isn't a good legal strategy for that reason.

But it can be a good social-engineering strategy: the "rule" is based on the hope that the person on the other end of it won't bring legal action in the first place, for fear of socially confirming their association with a small-penis'd character.

I think the point is that you can apply it to any shameful-enough aspect of the libel/parody.