Have you taken the time to politely ask him "what about this game is so interesting to you?" Have you asked him if he does mods, or what kinds of civilizations he's creating? Have you typed "benefits of minecraft" (without the quotation marks) into google and then carefully read the answers and reviews - by educators, professors, scientists, doctors and others who are not promoting the game or gaining anything by talking about the game (they're not associated with it, nor do they earn money by promoting it).
Do you speak respectfully to him? We had a neighbor once who used to say, in public, for all to hear (when referring to her son, in his presence) things like "that little &*$% is so disrespectful" and "that ($*%ing piece of (*$*% is always rude".
I'm not saying that your speech habits are ANYTHING like that. But if you are saying things like "dumb minecraft" directly to him, then that can be damaging to your relationship.
Kids are rude. I don't know, other than doing things like the Duggars do (that family with the 19 kids who keep their kids in their house even after they turn 21, and who restrict their jobs and friends to pre-approved situations, and who arrange their kids' dates and marriages), how to shelter your kid from a rude kid. The best you can do is to teach him that we do not sink to the level of others who have no social skills, and who can't speak respectfully. When your child is unreasonably disrespectful to you, you use your respectful words to kindly and calmly teach him how words hurt.
Sit down with him and ask him to show you about Minecraft. Meet him in his world. I asked my daughter to show me, and I built a crazy tunnel or something that had her cracking up laughing (at my horrible building skills). No, I'm not interested in Minecraft in the least, but she is, and we spent a pleasant hour with her showing me the ins and outs of the game, and all the math and science and tech.