This whole thing makes me chuckle.

I find eating period to be kinda gross. It's odd to me to sit across from someone, stare them directly in the face and watch them eat. Closer in is worse too.

The cultural norms are always interesting though, it's widely known that hocking (sp?) up, spitting and slurping are accepted as normal in China (forgive me if THAT part is a generalization, I'm not sure if it's regional). But you kinda just have to accept it and keep it to yourself I think.

If it's your family, or a close friend, maybe you mention it, anyone else and it's basically out of bounds unless they ask for a lesson in the matter.

When it's not a cultural norm, you still can't really say anything diplomatically imo. There's one particular lady in my life, VERY attractive...but I can't eat with her. It's awful lol. She's a mouth open eater and somewhat of a lip smacker too, it's too much. But I can't say anything, even in my head I get angry when I play it out haha.

The other thing is, once you notice it, you can't escape it and you overblow it. I would bet this guy wasn't as loud as the OP said, but you notice it, then it amplifies. Just like if you're already having a bad day, then this guy comes over, you might flip your lid even though it's something really insignificant.

I've never heard of Misophonia but I wonder if there's something else close, I CAN'T stand the sound of Styrofoam, it sends chills down my spine, coolers, packaging, it's all bad.