Being accused isn’t the same as being found guilty. Especially in the case of real estate, there is always a possibility that what he did to skirt to law and obtain that wealth may not actually be illegal.
That being said I don’t know enough on the laws or what he did, but it’s probably likely why China hasn’t killed him yet. They likely are doing a more drawn out investigation to find out if it’s their own poorly written policies that enable men like this to obtain that wealth and what to do to correct it in the eyes of common Chinese citizens.