"I might be off the mark on this but I think whacking Sammy might be more involved than just giving an order."..I see where you're coming from but, John did whack Castellano.
Sammy had a lot of respect from the guy's in his crew especially when he became under boss. When Sammy was bumped up so did a lot of his guys in his crew. I don't think they would risk their positions. Some that I knew were making big bucks after Sammy became under boss.