If the judges are good enough to tell that it's the wrong hop, you'll probably get dinged. But badly? Probably only a few points. Style problems tend to be less harshly deducted than technical problems. And if it has no technical problems and everything else is to style, it may still be the best pilsner on the table. In other words, you may loose points, but it's not going to automatically disqualify you from winning.
It's also quite possible they won't notice the wrong hop.