Not talking about this case in particular, but I spend a lot of time reading accusations on the scam accusations board and I can say that most of them are either fake or due to the user’s own fault (breaking the casino's rules).
There are valid ones, though, but they usually get resolved quickly.
Most of the cases are about withholding small amounts and the first thing that come to mind is "why would a reputable casino with a big user base would risk its reputation and lose many of its customers (lose money) for such small amounts". It just doesn’t make sense!