I don't support this. Facebook is a private entity.
Are conservatives going to sue DailyKOS because they don't allow conservative viewpoints? Will liberals sue breitbart because they don't have liberal articles?
I completely agree.
A private business can set whatever tone and tenor they wish.
Facebook is not a public service, not a town square, and not a public soap box. You are a customer in their business, you have no more right to legally demand they allow any speech (right or left) than you have the right to sue McDonalds to serve a vegan menu.
If you don't like what that business offers, move on.