The Texas Guard is under the authority of the governor unless called into active service. So there is no reason why Texas laws shouldn’t apply.
Texas State Guard is different from the Texas National Guard. The Texas Guard Guard answers only to the governor.
“The Texas State Guard is one of three components of the Texas Military Forces (TXMF), operating under the command of the Adjutant General of Texas and the Governor as Commander-in-Chief of all state military forces. The TXMF includes the Texas Army National Guard and the Texas Air National Guard.
The mission of the Texas State Guard (TXSG) is to provide mission-ready military forces to assist state and local authorities in times of state emergencies; to conduct homeland security and community service activities under the umbrella of Defense Support to Civil Authorities; and to augment the Texas Army National Guard and Texas Air National Guard as required.
Headquartered at Camp Mabry in Austin, Texas, the TXSG functions as an organized state militia under the authority of Title 32 of the U.S. Code and Chapter 431 of the Texas Government Code.”