I’m going to make this quite-clear — just in case you haven’t figured it out yet.
The US Military failed to adhere to the law and did not report a disqualifying conviction to the FBI, which would have prevented the Texas Church Shooter from buying firearms through legal channels. That man cracked open the skull of his infant child and beat his wife severely enough that he was tried by court martial, sentenced to military prison and then expelled from the service with a Bad Conduct discharge.
Under the UCMJ the failure to report this to the FBI as required by military regulations and thus cause it to be entered into the NICS databases so civilian agencies have proper notice of a disqualifying criminal conviction is a clear breach of a duty, and that is an offense.
Every single person involved in that failure must stand for Courts Martial or equivalent military tribunal for said dereliction of duty and effectively be made to answer as accessories before the fact to the murders that man committed, and be punished as provided under the UCMJ, including imprisonment for same.
These two citizens immediately took upon themselves the duty and risk of stopping a murderous jackass without being paid, without any special legal protections should they miss and hurt innocent people nor did they “up-armor” and cower in a stairwell for an hour first or wait until they could get an MRAP to where the shooting was taking place.