It is also the must bs of all arguments. Gassing jews was legal between 1937 (?) And 1945 doesn't make it right. Killing people trying to flee over your countries border to the neighbouring country was legal between 1949 and 1990 and that still is and was wrong.
Just because something was legal does not mean it was right then nor now
It only sounds complex and the workings are intricate. But the constitution is relatively straightforward in this regard. Germany uses a codified law system after all and its constitution is relatively new by comparison