Why was Billie Jean allowed to use the doubles area, and Riggs wasn’t?
Riggs agreed to that handicap- it was never a straight up match.
Because he would dance
On the floor
In the round
That did not happen. Riggs-King played to the same rules. You might be thinking of the 1992 match between Jimmy Connors and Martina Navratilova. Jimmy won, even giving up the doubles alleys to her. He also won a small fortune betting on himself. Jimmy gives an account of this in his book. Quite a good read by the way.