Aksai didn't wait for Mao's body to disintegrate on its own.
He took swift action, severing Mao's head before using a simple fire-element Spirit spell to incinerate the remains. His powers as a druid were mysterious.
Even though others might have seen him use the bloodline power on an enemy, as long as he didn't leave clues behind, they would just think he had used some kind of mysterious spell as opposed to a bloodline ability. Sometimes, half-baked information was more mysterious than a complete lack of it.
'Damn that old geezer. Who would have thought he still had some life left in him, especially after using multiple forbidden techniques. I lost almost 10 years of my life killing that skeleton,' Aksai cursed the old demonic cultivator even after his death.
