To be considered a "Vietnam Veteran," one must have served in or have flown over the land and/or waters of the conflict zone. The qualifications to qualify as a 'veteran' of any particular conflict are most usually spelled out in the criteria for the campaign medal for said conflict.
To qualify for the Vietnam Service Medal:
The Vietnam Service Medal is a military award of the United States Armed Forces established on 8 July 1965 by order of President Lyndon B. Johnson. The medal is awarded to recognize service during the Vietnam War by all members of the U.S. Armed Forces provided they meet the award requirements.
The full award criteria can be found here: Award criteria
It is entirely appropriate to mention that his service in Germany was during the Vietnam War era. A good profile example is our very own Dorothy Barry:
Dorothy Barry is a Military Veteran.Served in the United States Army 1968-1988 attaining enlisted rank of Master Sergeant (MSG) E-8
Served in both the Women's Army Corps and the US Army during the Vietnam War, and peace time.
If his mission was in support of the war I would mention that. Many veterans had service in other Gulf countries but didn't fight in Iraq. I know of one officer who treated evacuted (injured) servicemembers at a hospital in Bahrain who was awarded a medal for support of the war even though she didn't qualify as an Iraq veteran. For her profile I would say that she served in Bahrain in support of Operation Iraqi Freedom. If she was stationed there but didn't support that particular campaign I would do as Dorothy has done and say that she was in the Army stationed in Bahrain during the Iraq War.
One of the best ways you can honor his service on his profile is with the Veteran Recognition Sticker. I don't see what unit he served in. If you can share it we can help you to find the appropriate category and sticker details.