Think carmine persico also vote yes but the other 3 familys said no. This came from greg scarpas intell and its almost probaly the only thing i didnt believe.
Why do you think it isn't believable? Knowing Persico, he seems capable of voting yes for such a dumb decision. He had already ordered a hit on a prosecutor who wasn't even that much involved in investigating the Colombo family, he was investigating the Gambinos (the triggermen botched the hit by killing the prosecutor's father by mistake); voting in favor of killing Giuliani too wouldn't be out of character.
Don't know if this is true, but I think in one of the documentaries it was said he couldn't even keep calm while reading Michael Franzese's book, tore it to pieces and threw them against the wall; it takes nothing to get him enraged, and he had reasons to be pissed at Giuliani theoretically...
And Gotti was just plain dumb. If somebody in the American mafia leadership at the time could vote yes for such a high-profiled (and counterproductive) planned hit, it would be Persico and Gotti, makes sense imo.