Do you have an idea why Venus Williams would want to wear this?

Today i was watching the tennis at Roland Garros.
Venus Williams was playing Arantxa Parra Santonja and she was wearing (possibly NSFW) this undies.
First i was wondering if i saw it right and when i was sure i was, i was pretty amazed (and a bit excited to be honoust).
But why would one want to wear this kind of underwear (in public)?
Extravagancy? Advertise her clothes brand? Confuse her rival?
Would she have been allowed to wear the same had she been playing the US Open (i am thinking about the Janet Jackson Super Bowl controversy)?
What do you think, is it none of our business or is she crossing a line?
Any other insights?