The fact that the guy was born and named Jeep BEFORE Jeep was manufactured proves he did use the name first.
That fact alone means the guy must be ancient. Jeeps were "Jeeps" in WWII.
It reminds me of a similar lawsuit in Springfield, Ohio.
There was a very old bar & grill called "Burger King" that really HAD been open before the chain started in 1954.
The little guy won that round, and ALL BK's in Springfield had to change THEIR signs.
So it looked just like the usual 2 bun BK logo, but the restaurant used "Home of the Whopper".
When the guy died, BK was allowed to use their regular logo.