California is one of the states that prohibits private citizens from making audio recordings of people engaged in private conversations without the awareness and consent of all parties to the conversation.
Section 630-638 of the California Penal Code authorizes punishment of those who make such unauthorized recordings
"by a fine not exceeding two thousand five hundred dollars ($2,500), or by imprisonment in the county jail not exceeding one year,"Furthermore.
Except as proof in an action or prosecution for violation of this section, no evidence obtained in violation of this section shall be admissible in any judicial, administrative, legislative, or other proceeding.
If illegally recorded conversations cannot be used in a court of law, then they shouldn't be usable as evidence by private organizations such as the NBA.
Did the NBA ask Sterling if he was aware his conversation with V, Stiviano was being recorded? Did the NBA request a medical/mental evaluation of Sterling to determine if his medical condition including age and cancer treatment could have affected his participation in the conversation?
It could be argued that some of Sterling's comments are irrational. For example, he said he didn't mind Stiviano having sex with some individuals whom he didn't think she should be seen in public with. Some medical conditions might be detectable from his speech by an experienced doctor,
The most common interpretation of Sterling's statement about Stiviano coming to games with black players is that he is racist. However, he might have been attempting to warn her about the racism of others in an ineffective manner. Some comedians like to joke about NBA players fathering children all over the country based in part on the bragging of former NBA players such as Magic Johnson and the late Wilt Chamberlain. I suspect that the whole situation is exaggerated, but many people believe it. Sterling may have been worried that those who believe this stereotype might think Stiviano is sleeping around.
The whole incident involving Donald Sterlings smells. It sounds like a bad soap opera story line. Why would V. Stiviano make such a recording unless she was conspiring with someone to discredit Sterling? If the purpose of the recording was to get the NBA to take the franchise away from Sterling, the NBA needs to investigate because someone who would use such a tactic to gain control of an NBA franchise is morally unfit to own a professional sports franchise. For example, a person who engages in morally questionable actions might be potentially subject to blackmail by gamblers who might seek inside information about players' medical conditions.