As per IMDB, he says *“Sometimes when people go to Vietnam, they go home to their mommas without any legs. Sometimes they don’t go home at all. That’s a bad thing. That’s all I have to say about that.” *
It’s possible he was hard of hearing. It wasn’t until the 70’s that a lot of mildly “mentally handicapped” kids were dx as being HOH.
Personal data point - my mom’s sister, who just turned 66, is mentally about 10 or 11. I know she went to school at least thru the 10th grade (maybe 1962 or 63), but I’m pretty sure that was all. She can read and write on a very elementary level, she knows how to tell time - in fact, she’s obsessive about taking her meds on time and being fed at exactly the same times every day. I have no idea what her IQ is, but she does have a pretty remarkable memory about certain things. On the other hand, she’d never be able to live on her own - even I recognized that as a kid.
I remember my mom telling me the doctors recommended that my grandparents have her put in a home, but they refused. I’m pretty sure if she was a child in the system today, she’d have had a better outcome, although I still doubt she’d have learned to be independent.