I asked you first-- and it was a serious question. Does the POTUS have authority to call out the National Guard in a case like this?
If I'm not mistaken, LBJ called up the Guard to protect the safety of civil rights marchers in Selma, Alabama, in 1965. Whether things have changed since then, I don't know. But given the broad powers of the Presidency, I don't think it unreasonable to suggest that he could at least do something.