In other words the National Guard can only be deployed by a governor for law enforcemnt purposes.
A Brief descirption of the U..Miliatry
National Guard forces normally operate in state active duty (SAD) status when responding to disasters and civil emergency. During such assistance efforts, one of their primary functions is to reinforce law enforcement agencies. The National Guard, once federalized, like the Active Army, becomes bound by the Posse Comitatus Act and loses the ability to act as a law enforcement agency.
Posse Comitatus Act
Exactly....Once NG is federlized they cannot perform in LEO actions..that is why you keep the NG at the state level.