Death Monarch stance against the Crime Alliance is well known. You me him and it is like you meet the Grim Reaper.
There is only one outcome. Meet him and you're dead. He could not be bought like the Senators of the Republic or be coaxed like the nobles of the World Government
He could not be bullied; he could not be negotiated with. So, there was never any negotiations or any contact with Death Monarch factions because from the very beginning the solution to them have always been exterminating them
It did not matter if their reason for existence is logical or not. Since Death Monarch wanted to kill the., what reason is sufficient to stop that stubborn godlike person?
With such a reputation, it is no wonder that the moments the members of the Crime Alliance in the island and all over the Turbulent Sea acted like the way they did