It is an immoral crime to pursue these old men.
It's not like you talking about a volunteer military like you have today. WW2 were conscripts who were either drafted or killed. The only reason they are alive is because they obeyed their master. The individual merits of each guard is lost with time. All you're attempting is collective punishment.
Men like
Johann Breyer should be left alone.
There is no pursuit of normal German soldiers (Wehrmacht.)
The vast majority of German soldiers were not treated as or pursued as war criminals.
The war criminals are essentially all SS guys. They are card carrying Nazis who partook in extermination and rape on a grand scale.
Now, this Johann Brever claims "I'm Innocent, I didn't work at the camp where we killed people, I worked at the other one where we had them alive as slaves!"
If there's enough evidence to bring him to trial, then he should be given a trial, and, a jury should decide if it's worth convicting him. Then, a judge can sentence him if need be. Yes, it sucks at the age of almost 90 to be dealing with this crap, But, better late than never.