This is nonsense that I wrote in the discord xD
Corazon had the audacity to appear in Sabaody because he heard a rumor that Law would appear there. (Cora continued as a marine but with simpler jobs after recovery) Law thought Cora was dead but when he saw him, they both knew they would never be apart again.
Could it be considered that Law "kidnapped" Cora from the marines?
Sengoku receives a report that a pirate has kidnapped Cora. Sengoku is alarmed until he sees that it's Law who kidnapped him, and his face softens and hes like... "It was a matter of time before this was going to happen..."
Sengoku assumes that Cora will no longer return as a marine, but rather that there will most likely be a reward poster for his son in a short time.