For example, if you say the Colosseum is to Rome what a roller coaster is to an amusement part, you are not saying that the Colosseum is similar to a roller coaster. No, what you're comparing is the Colosseum's relationship to Rome and the rollercoaster's relationship to the amusement park.
xg15's analogy isn't meant to equate Black people in America in 2020 to Jewish people in Nazi concentration camps. Rather, it's meant to compare the irrelevance of intra-Jewish violence in the face of Nazi violence to the irrelevance of intra-Black violence in the face of police violence.
Always surprising to me how the basic structure of analogy is so commonly misunderstood.