Why did OJ's prosecuter agree to his racist jury?

Don't know that they were. There was reasonable doubt before the LAPD planted evidence and told lies. There was no smoking gun. No human was on Bundy Drive to witness the murders. But I guess you may be one of many white Americans that believe OJ did it because you just feel like he did it. Sorry. That's not the way it works when you're judging whether someone will spend the rest of his life in jail or be executed. Jurors weigh the evidence, and if there's any doubt whatsoever, you must find not guilty.