The goalpost was 20MB, there was an attempt at a compromise to 8MB

This is not what happened. Gavin showed some models that he created that were meant to prove 20MB was safe. However, people quickly noticed that he had an arithmetic error in his calculations and that 20MB isn’t safe even by Gavin’s own model.

When corrected, his model showed that the actual safe block size was 8MB, which is why Bitcoin XT corrected it to 8MB. Nothing to do with compromise.