I dont think he had the stomache, the muscle or time for an all out war. He was under house arrest, the feds were "so far (his) ass he could taste brill cream", alot of his guys were with Tony , and those who werent didn't stack up to Tony's support level. Furthermore, he wasn't doing well health wise. He was just over it I think at that point. He tried, he lost, he rolled over and died.