Part of the issue is

If you kill someone on your own you have a better chance to get away with it

Like Basciano ordered the Pizzollo hit
He had an acting capo that flipped and massino that flipped

So if your order the murder:

1) there are so many CI's that the Feds know about it right away
2) if the guys in on the hit flip they now have a "GET OUT OF JAIL FREE CARD"

So you have the chance of getting caught red handed
And then you have to worry about the guys who did the murder telling on you

Way too risky