But the Alabama National Guard could simply refuse to be federalized. County sheriffs could unite to declare the order null and void.
...which would involve defying a direct order from their Commander-in-Chief. That has never happened, except when states seceded during the Civil War.
When President Eisenhower federalized the Arkansas National Guard to carry out a federal court's school desegregation order in 1957, he was afraid they wouldn't obey the order to be federalized, and he called up the 101st Airborne Division of the regular U.S. Army in case the Guard resisted, but the Guard followed federal orders.