Right after WWII, the US rehabilitated its “enemies,” Germany, Italy, and Japan, while starting the Cold War with its “ally,” the USSR. Rehabilitating Germany & Japan was important for the US’ containment strategy against the USSR.

If we see that Germany is winning the war, we ought to help Russia; and if that Russia is winning, we ought to help Germany, and in that way let them kill as many as possible […]. — Senator and future president Harry S. Truman, 1941

https://en.wikipedia.org/wiki/Walter_Hallstein

In 1935, Hallstein attempted to start a military career alongside his academic duties.[17] In 1936, he managed to integrate a voluntary military service in an artillery unit.[17] In the years between 1936 and 1939, he attended several military courses[18] and was made a reserve officer.[17]

Hallstein was a member of several nominally Nazi professional organizations,[g][19] but he was not a member of the Nazi Party

Not the worst nazi but the voluntary military service under the Nazis seals the deal for me. Definitely a Nazi.

He had no choice

Ratzinger's family, especially his father, bitterly resented the Nazis, and his father's opposition to Nazism resulted in demotions and harassment of the family.[20] Following his 14th birthday in 1941, Ratzinger was conscripted into the Hitler Youth – as membership was required by law for all 14-year-old German boys after March 1939[21] – but was an unenthusiastic member who refused to attend meetings, according to his brother.[22] In 1941, one of Ratzinger's cousins, a 14-year-old boy with Down syndrome, was taken away by the Nazi regime and murdered during the Aktion T4 campaign of Nazi eugenics.

Did these people get promoted to the head of the USSR’s space program or the chief of staff of the Warsaw Pact or the UN Secretary General or the the Head of the Soviet Socialist Republic Commission?

No, the were used for their technical knowledge and allowed to live quiet lives in obscurity, away from any political power.

The keywords here being "as war reparations".

Nazis were put to work for their crimes not given a new name and passport and a high paying and respected career.