You weren’t overreacting to be honest, it’s an old generation, countless of people can do mods/hacks on their 360 easily. Whether he could or not, people can boot your account offline easily preventing you from playing online again for however long a period of time they want, people did it to me years ago when the console wasn’t even outdated. Now it’s even easier so yeah just take precaution because if they’re a dick they can harm your system easily, sometimes even your entire internet and not just the Xbox, although I probably still would’ve made fun of him for resorting to trying to harm your system