Toulon
I think we need to keep things in the proper context here.
The fans weren't booing Naomi. The fans were booing the manner in which the match ended. And Naomi undoubtedly had fans in the stadium that night who weren't pleased in the least with how things were handled, by neither Serena nor the chair ump.
It was just (imo) an avoidable situation by both Serena and the chair umpire. Serena was overly confrontational. The chair umpire wasn't in the mood to be even slightly diplomatic whatsoever. It turned into a pissing contest. The chair umpire won the battle, the match was marred by controversy, and the fans who paid who only knows how much to be in attendance there felt short sided.
It's not that I don't see the other side of the story. Just that I think a lot of critics don't care to consider the other side of the story as well.