He had to go, more than a Chris, or more than a Paulie who layed in bed with NY.....
Tony was a guy that defended his cousin to the end, even if that meant losing all face in his crew(even Sil) and going to war with NY.....Even originally Tony stopped Chris from handling that........
Tony telling Ralph to kill Jackie was a maniacal sociapathic way of making both Ralphie and jackie pay, he could have let Chris handle him.................
You have to understand the constant pissing match between Ralphie and Tony after this he fukks Tony's sis, and after that Tony fukks Valentina, then after that Ralphie kills his horse, then tony killed him............It was a constant back and forth breh, down to the stripper he killed who Tony didnt give play because Ralphie was fukking her, then killed her............Jackie's death was more about punishing Ralphie
What don't you understand about Jackie robbing and shooting made men?