Those dudes would have been too old for the WWII draft.
They were way too old for the WII draft and some might have already received a draft notice for WWI. My grandfather received a draft notice but was deferred because he was missing several key toes (important for the infantry) which he accidently severed cutting wood barefoot as a 12-year old.
Probably was the voter rolls. My grandfather was born in 1886, lifetime republican. I’m guessing that when he died in 1986 that his name immediately went onto the Missouri democrat voter rolls.