I was thinking the same thing - just Google the name. It is astonishing what is on the internet.
I think he might try calling the local libraries and newspapers there in Dubuque to see if there might be descendants. It’s sad but that probably IS the chap. He would’ve been 18 in 1918, prime age for a young man to be at war then and knowing what happened in WWI, he very easily could have died in the 30’s if he’d been exposed to the gas or other poisons. And of course, people died of pneumonia and other things rather easily back then.
What are the odds? It even says AEF on the stone.
/johnny