I think Sliwa is just playing hurt for ratings.
Kuby (whose Mommy was a commie) had little choice. Testify or go to jail.
If the jury believes that Gotti left the crime business by a certain date, then the statute of limitations will make it impossible for the jury to convict Gotti of having Curtis beaten and shot to within an inch of his life.
Kuby will testify that Gotti told him he was out of the crime business meaning Gotti can be acquitted even tho guilty.