I've also been in the FAR bunkers. It's relatively safe there for certain types of failures. Their underground bunker is much safer for more situations. But, extra distance is the best way to avoid debris from a CATO (on the pad or during boost).
First, there's a debris radius which is fairly well known for the size of the motor involved. This can be seen in the recent P cato at FAR: everything fell within a 250 ft radius. The difference at FAR as compared to a TRA launch is that the FAR bunkers, buildings, vehicles, and other launch pads are all within the 250 ft radius. At a Tripoli launch, the safe distance for a P is 2000 ft. One of the videos of the recent P cato was taken from about that distance: spectacular view but well outside the debris field. Second, the extra distance equals extra time to react if a piece heads your way. There's no time to react in a bunker at 200 ft if a chunk goes through the open viewing gap or through the roof. And third, your body and other assets occupy a smaller fraction of a degree at increased distance... the probability of coinciding with the path of a chunk is reduced by 2*pi for each doubling of distance. If one includes the limits on types of metals, reducing the ballistic coefficient, the probability is further reduced.
Insurance underwriters take all these factors into consideration. So, why doesn't FAR increase the distances to allow them to get the same insurance as Tripoli? They have no choice because the land they own is about 10 acres (660 x 660 ft). Even just for an M it requires special placement of the pad and people to get 500 ft. Another requirement to meet TRA safety code (and NAR and NFPA 1127) is to have 1500 ft from occupied buildings. If people are present at the adjacent RRS site, it's difficult to comply. Even if a pad were set up at the furthest point on the south end of FAR's property, almost all the RRS site falls within 1500 ft to the north. There's little or no coordination between the two groups when scheduling. There was definitely an effort to avoid interfering before the student group's P launch because the rocket was taken down and the pad was moved further south.
With that said, FAR is a unique place to test projects that otherwise wouldn't fit in with the focus of other rocketry organizations and launch sites. The TRA announcement makes it clear that Tripoli's insurance doesn't cover a TRA member's activities there. A reminder that you're on your own liability when at FAR. That's also reinforced by having to sign a liability waiver at FAR. Hopefully, everyone who attends understands the differences and the risks.