Who would have the most to gain by Colombo going? Carmine Persico by far, mind you he was not on the street but had a very strong crew. Michael Franzese believed that Carmine Persico played a role in his father's(Sonny Franzese)bank robbing conviction. With Franzese gone who else would stand in the way of Persico grabbing the top spot? With his strong crew on the street Carmine could easily know how unhappy people were w/Colombo. So Snake hires a black man to do the job knowing that Gallo will catch the heat for it and not the Persico crew. Gambino is fine as long as Colombo goes away and the civil rights B/S dies with Colombo & the hired hand(Johnson).