This case appears to have some substantial grounds:
In addition to the case itself, this case could have implications for the military justice system - its verdicts would need to be reported for use in the NICS DB. It could also bring the possibility of legal consequences to states that are sloppy about reporting relevant mental health information.
Just think. If the very officials responsible for making the system work could be held responsible if it did not, how many would want that sort of exposure.
Sure, you can argue that they would go after innocents with torches andd primitive farm implements to ensure their personal hindparts wouldn't be on the line, but they'd have to stop all of the crazies, and history has shown no law to be that effective.
Likely, they'd use this as an excuse to push for red flag laws, but then those become an additional liability, and subject to lawsuits for abuse (overzealous enforcement). Once that door is opened, it swings both ways.