Sammy's deal was that he wouldn't testify against anyone in his old crew.
And an off the books deal with Gotti Sr, son for a son.
If Gravano left Gotti Jr out of everything Which he did
Gotti Sr. would not come after Gravano's son.
The last hit Sr. ordered I forget the name in the parking garage the work was done by Jr's crew, he was capo at the time Gravano totally left Jr out of the plot