He was born in 1954, so he would have been around 26 years old in 1980.
Also, he graduated West Point in 1976, so if he was in the military at the time you were in Korea, he would likely have been an Army officer, probably either a 1st lieutenant or Captain.
If it’s the same Horiuchi, he was the Headquarters Commandant of Camp Howze, Korea. I once thanked him for getting heating oil to the BOQ (I woke one morning to find my BOQ room to be about 20deg because the oil tanks had not been filled). He looked at me like I was some sort of invertebrate life form. He was one of the coldest individuals I’ve ever met in my life.