I am hoping he is taking part in a demonstration or re-enactment, and not some old fool proud of his Nazi past...
I used to go every year to a fly-in with all kinds of people dressed in WWII uniforms. They all took pride in trying to be as authentic as possible. One year a group of about fifteen guys was dressed in uniforms almost everyone there had never seen before. They were Russian special forces. Neat looking uniforms.
This looks like one of those re-enactments or fly-in.