The decision essentially complies with the 11th amendment as written -granted, it is mostly interpreted to the Federal courts, but it's an obvious extension to prohibit suits in foreign states too.

"The Judicial power of the United States shall not be construed to extend to any suit in law or equity, commenced or prosecuted against one of the United States by Citizens of another State, or by Citizens or Subjects of any Foreign State."
It's not even a conservative or liberal issue imho. People are just making headlines for clicks.