BESD???

I've ran into this guy a few times on edoPro, he's running Blue Eyes Shining Dragon, but this card is unsummonable in Goat, no? Like BEUD isn't legal, or am I missing something? I've asked the few times I've encountered him, but he just says "sure". It's kind of driving my crazy, does he not know how the card works, or is he into something crazy I'm not seeing?