Well, well... we have a very difficult and tricky situation here, and finding the right words will no doubt be a challenge without comparison. Let's see:
- If you tell him it's tech death, he'll see it as an insult to his knowledge and intelligence, and you'll lose a fan immediately. If he likes it because he thinks it's core, he definitely won't like it if it's not core. People are digital like that. Also, you'll be known as the hugest asshole ever on every social media in the world. I've seen it happen.
- If you let him think it's core, you'll lose a fan, because people usually grow out of core in two months. You'll also be known as the hugest asshole ever on every social media in the world, because core musicians are just that by default. I've seen it happen.
- If you try to carefully coax him into the right direction to realize himself that it's tech death, and not really push it, you'll lose a fan, because no doubt he'll be really ashamed of his comment when he realizes he sounded like an idiot. He'll likely listen to dubstep or something for the rest of his life, and deny the conversation ever taking place. You'll also be known as the hugest asshole ever on every social media in the world, because manipulative bastards appear as smug bastards, and trying to influence people's minds with jedi mindtricks is considered assholish behaviour everywhere. I've seen it happen.
TL;DR: I think the only option is to punch the mothafucka out, like, immediately, and yell as loud as you can something like "We are The Turnip Singers, and we bring you destruction, hellfire, and tech death! Anyone thinking we are core will be forced to eat choice cuts from his own genitalia!" That will make the other two audience members see the truth, and you'll get a few more fans to replace the now-wheelchair case, because people like brutality. You'll also be known as the hugest asshole ever on every social media in the world, because punching people to death is not nice, but in this case, it works in your advantage, because Mustaine, and the next phase is pure sweet profit. I've seen it happen.
Ok, we are done here. Oh, how I love sorting people's lives and other very Important Questions out! I should start a column in a newspaper or something.
Chest wounds suck (when properly inflicted).