No, he wasn't a border guard, he was based out of one of the two Würzburg kasernes. Since he was a combat engineer, in the event that everything went boombastic on the IGB, he'd be moved up to the Gap to be the speedbump.Point Alpha?
-> That then counts as Franconian dialekt ^^ (according to this).
Before I was born, he did another tour in Germany in which he was stationed in Hanau as part of the Spearheads (Third Armored Div.), which was also assigned to cover the Gap.
Anyway. The accent. I'm familiar with Ostfränkisch, but I don't actually pronounce words that way. Most of the German I got was either on TV (because AFN sucked ass) or transmitted through the DoD school system/parents. Subsequent participation in German classes as grade-boosters for my secondary education in the United States has if anything reinforced the Hochdeutsch.