That threat has to do with Ritchie's relationship with the Rosatos. Not anything about Corleone. Hell, they wanted Corleone dead. They were probably in on the attampted hit with Roth.
"Io sono stanco, sono imbigliato, and I wan't everyone here to know, there ain't gonna be no trouble from me..Don Corleone..Cicc' a port!"
"I stood in the courtroom like a fool."
"I am Constanza: Lord of the idiots."
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