Well, she's not the first person to imply that the BBC demonstrate favouritism, some on here believe they've seen evidence of it, (including me). So as she was an "insider" for years, she'd have an even better perspective on it, than mere viewers.
She won't be coming back, so why shouldn't she say what she thinks?
The rest have to pussy-foot around as it doesn't do to upset the BBC, as other pro dancers have found to their cost.