Easy Google search would have told you this is 100% false. Big 3 season is on weekends between June 15 - August 18. WNBA season is from May 14 - Sept 19 plus playoffs. The initial comment about how only two dates would "conflict" implied she could play Big 3 on Saturday in some random city and then join the Fever on Sunday for their game, or vice versa - good luck with that one.
Not to mention the Olympics are July 21 - August 14 (WNBA takes a break). But definitely play in the Big 3 over that, because $$$ right?
Injury risk would be elevated, plus the ball is a different size / weight.
It would be a sideshow and her brand (and potentially all of women's basketball) would be damaged by going up against 6'6" former NBA players. She doesn't need any of that to make bank and be successful long-term.