Oh, really? I bet if he leaves the borders of the US at all he carries a real passport. No customs officer will put up with this. They have zero sense of humor when it comes to documents.
Back when I worked in retail someone tried to get a credit card with a fake "gov" ID. We called the cops. A detective showed up real quick and confiscated the ID while interrogating the guy.
Tried to get the "provider" out of him and cut him loose. Told us someone has been peddling the IDs and they were on it.
That was 20 years ago let alone now. So ymmv on that side hustle.
Imagine if this worked, and people could just exempt themselves from the law by carrying a card that says "diplomatic immunity" on it. Everyone would do it, you'd be crazy not to, even if you weren't planning on committing crimes, just to prevent the possibility of a (potentially unjust) arrest or conviction.
And once everyone is above the law, you basically have The Purge, which devolves to more of an Escape From New York kind of vibe, before finally landing in Mad Max territory.
Or, alternatively, we recognize that the card works just as well for the authorities, who can't be charged with anything for ignoring your diplomatic immunity.
"You heard 'em. Cut off their access to public services while we arrange transport to their homeland of... Oh! Heaven! Hey! Have Phil get the cannon ready!"
It might even encourage people to commit crime. I know I'd use it to tape Monday Night Football without the expressed written consent of ESPN and the National Football League.
These people can't be this braindead. It doesn't take a genius to understand that countries have to also recognize their political status to make it real in any way other in than their minds.
Only found out about it recently and it just seems bonkers, like in what state of mind do you have to be to think you can just wish away the laws of the country.
It's also a thing in other countries. In the Netherlands there recently was a news article about someone who got financially ruined because she and her husband stopped paying taxes and rent because they claimed to be sovereign.
Probably imported the idea from the US, where it's much more visible.
Nation states are a figment of our imaginations. There is no American particle or German substance. Sovereign citizen are just a low budget version of that particular game of make believe.
The funny thing about this is that if this were a real thing, the issuing agency would necessarily possess all of this person's precious bodily fluids personal information.
That eagle hologram on the top looks suspiciously German. Going through the versions the most like likely (wing shape, size of tail, various details) seems to be the kleines Bundessiegel, small federal seal, this one.
So tough luck, this is actually a personell identification card of the limited liability company making up the German federal level.