I think you are wrong. Look up what happened on September 24,1957 in Little Rock, AR. President Eisenhower federalized the Arkansas National Guard. The Little Rock mayor called for help.
I'm not familiar with what happened then, but just from what you said it appears the Governor must have requested the action. Was it a natural disaster? And has anyone in New Orleans asked the President to federalize Guard troops?
The Guard was federalized in Little Rock, not for national disaster, but to enforce a court desegregation decision.