That command structure is literally on the DC NG wedsite. Your sources are lying to you.
“As such, the Commanding General of the D.C. National Guard is subordinate solely to the President of the United States.”
Read the below, but if you're short on time, here's the short of it - "By law, the D.C. National Guard serves exclusively under the command of the president." The president could've at least ordered the DC Guard to the capital at any point, and he did not.
Even if he had, it does not stop...