I think it also had something to do with respect for Carlo Gambino. Everyone still loved and respected Carlo even if they looked the other way towards Big Paul's death. Regardless of whether alive or dead, nobody would want to be the one that kills the legend's son.

And LE attention was already high enough from the Castellano hit. Would Gotti really want to add to that by killing Carlo's son?

"I die outside; I die in jail. It don't matter to me," -John Franzese