Was your initial employment based on the condition that you provide the social media? If not, then they are invading your privacy by requiring it now. If you know any lawyers, ask them. See if you can get one on contingency to sue them.
My employment is that of a security guard. In the security guard industry, they can pull your contract anytime they want even if it is because it’s Tuesday.
It’s very vulnerable. I’m in a spot that I thought I was safe, but this data mining has filtered down to me.