I hope you are right.
On the other hand, these killings did take place on Texas soil. Maybe the state should prosecute?
While not technically impossible, I have a better chance of being crowned King of England. It's a military shooter, with military victims on a federal reservation. The Feds could assert jurisdiction if they find evidence of a broader conspiracy, but for Texas to get a crack, both the military and the feds would have to pass. That's not going to happen.
Occasionally, you will see state authorities prosecute crimes committed on federal reservations. Most frequently, these crimes are domestic in nature ie, a civilian spouse hits her military husband over the head with the frying pan. Since she's not in the in the military, and there's no federal statute against braining someone with the Calphalon, the the feds let the staties prosecute. That's not going to happen here.