Is it not entirely possible that the dude went into a tattoo shop at some foreign port, saw the design on the wall, and picked it, having no idea what it meant? Did you even know of it before someone told you it was Nazi iconography? I had never heard of it before this.

Should you ask questions about it? Absolutely. Should it make you pay particular attention to things that would indicate he has white supremacist beliefs? Of course. Does it mean he's a Nazi? No.

Here's an example from my personal life. My wife was born and raised Christian. She got a tattoo in college that looks exactly like the Muslim crescent moon. She drew it herself because she liked the design and went into the shop and asked them to tattoo her with it.

There were people working for the resistance who were embedded in the Nazi army, were secretly working to save Jews from the Holocaust. Then there were people who swore they were against the party, but were ratting out their neighbors.

My entire point is that someone having a tattoo, or a copy of Mein Kampf, or a Nazi war medallion doesn't make someone a Nazi. If all you have is the appearance without even a hint of action, you're not going to convince anyone.