A bit off on his age in 1989; he was actually 75. Otherwise he would have been pretty young to have served in WW2.
65 in 89 implies 18 in 1942; that doesn't seem too young to me?
He would have been 17 at Pearl Harbor. IIRC, the average age of a US soldier in WW2 was around 26. Either way, he was 75 in 1989, so his age when the US entered WW2 was 27, roughly matching the demographics.