Of course, what Ma Chao learned most adeptly was the Han etiquette regarding the reverence for elders. After all, in his eyes, Zhang Fei's behavior towards him and subsequent rituals were not unrelated. It would seem that in the future, even if Ma Chao falters in other areas, he will never overlook matters of loyalty, filial piety, integrity, and shame!
As for why Fa Zheng didn't trouble Ma Chao, it was because he understood his mission. His task wasn't to clash with Cao Cao or Ma Teng but to await the outbreak of the Yuan-Liu war and then deploy the mediating army.
After witnessing Ma Chao's performance, Fa Zheng was actually quite satisfied. Standing at his current elevated position, he could oversee everything that once was, with many events reduced to ephemeral trivialities.