I would think that if you were in the bullet business, what with gun powder and all, it would be beneficial to construct your building out of stuff like metal, stone, and other materials less inclined to burn.
Part of the building, but not other parts. Stronger materials contain explosions better, generate more pressure, and generally make for bigger booms. Even though they may be more fire resistant.
Thats the intent, but I can show you what's left of an earth covered igloo in northern California. They found chunks of concrete and parts of the steel doors on a mountainside about four miles away.
An earth covered building with steel doors and made of concrete would be about one of the most dangerous explosive containing buildings if it actually did have enough pressure to blow.
By definition the much stronger materials will trap the pressure in longer, generating much higher pressure and resulting in a much bigger explosion when it goes.
If you put a weak firecracker on your flat palm it will likely burn you. If you close your fist around it it will likely blow off parts of your hand.
Similarly the tougher the casing around an explosive the more pressure it generates before it explodes. Steel will explode with a lot more force than paper for example.
As will a steel or concrete walls compared to a plaster and wood.
apparently this company does not concern themselves with government mandated safety protocols.
Without knowing the layout of the building who can say?
A properly designed test area would actually be set up to blow up separately and away from the people inside the building.
Making the path of least resistance away from the people and outside of the building. Channeling the explosive energy away from people and the rest of the building.
So without knowing the layout of the building and test area it is hard to say if it did not work exactly as intended in the event of an explosion.
It is kinda like crumple zones in modern cars. It sure makes them take a lot of damage from much more minor impacts, but it is intentional so that the damage is predictable and can be engineered to send the force in a desired direction.
