Doesn't make sense to make it mandatory to login using facebook or twitter in a gambling site. That sounds fishy to me. But if I badly want to try out a gambling site I might consider making up a fake twitter , google or even a facebook ID. Will never you my real one!
Yeah even i would feel something weird about the site as to why it is compulsory to sign in with social media as it has most of my personal details which i wouldn't like anyone else to know about. If anyone does come across a site with compulsory login with social media don't login blindly check few reviews first or make a temporary account to sign up