the feds would not have cut a deal with gotti. in fact both bruce mouw and George Gabriel have stated that gravano was lucky to get the opportunity to flip. They already had a lock on that case with the tapes, gravano was only brought along as window dressing ,to corobarate it. It was debated weather to let him flip. No way they offer gotti the same shot...they want to see him rot.
And for all his other flaws, John Gotti stood tall and took his time. That was just in him...its who he was. you cant wipe away 50 years of indoctrinating without giving away who you are. You have to respect that.