The Common Core is not a national curriculum, because it is not a curriculum at all. It is only a set of standards, and that's completely different from the scope and sequence of curriculum planning. But like that terrible Match.com date you went on, the standards/curriculum distinction only looks good on paper.
It may be that the prospect of an active, informed, educated citizenry is so frightening because it would begin to question how the United States ended up with so many elected officials who are not only ignorant about science and history, but are willfully ignorant and want to impose their ignorance on the rest of us.
We can call the CCSS the Common Core State Benchmarks, Guidelines, Requirements, or Ensigns for all I care. But this does not eliminate the fundamental truth that the CCSS is a curriculum. And like many iterations of curriculum, it is sullied by the ideologies and personal ambitions of its architects.