That same situation (Judges not knowing the correct ruling on Dreadnought) screwed me out of a top 8 in a side event at Grand Prix Atlanta. My opponent was playing Full English Breakfast variant, and had Survival in play. I was playing Stax, and had him about halfway under control after destroying all his lands that produced green, but he had 2 BOP's and a Wall of Roots, so I welded his 'nought into play for his Mox Emerald (his only remaining non creature green source) I thought this was frickin' brilliant, since I knew the correct ruling on the 'nought ( I meant to wipe him out of green completely by forcing him to sac his critters. He just looked at me like I was nuts, called a judge, who misruled. I appealed, the second judge misruled, and I couldn't get them to go get the level 3 that was there. Pissed me the hell off, and I ended up losing cause I couldn't stop him from Survivaling.... At least the prize that day was just a foil Serra, so I didn't miss too much, lol...