Donna, I reiterate that I am no expert. I have some experience from researching my own family re WWII. Loving both our vets and history, I have read quite a bit and talked to quite a few WWII vets. Having cautioned so...
302nd Infantry received campaign credit for Rhineland and Central Europe, but also for Northern France and Ardennes-Alsace. Given the time periods for these campaigns, and if he had been in 302nd at the time, it seems unlikely that his discharge would state Rhineland and Central Europe, and not Ardennes-Alsace. This suggests to me that, as suspected, he may have spent most of his service in another outfit, and had been recently transferred to 302nd when mustered out of the Army.
You had naturally assumed that he was in 94th ID. However, it may be the unit roster you acquired based on that assumption was really of no use. (Apparently, from the responses you have received that was the case.) I believe if he had spent much time in 302nd Infantry some of them should have remembered him. I say this because a First Sergeant would be the highest ranking non-commissioned officer in an infantry company (typically around 175-180 men) and, I think, fairly visible/notable to the rank and file.
So, how to investigate whether or not these conclusions are accurate? Do you have any photos of him in uniform which show unit insignia? Do you have his uniform, or decorations removed from his uniform which might include unit insignia? Do you have old newspaper clippings that might have unit info? Did he belong to any vet groups (VFW, American Legion) where he would have left service info or shared service info with other vets? Do you know if he ever applied for, or received, benefits from the Dept of Veterans Affairs?