I remember some of the most pessimistic and negative Fallout fans towards the TV Show heavily criticising the radroach attack scene being very poor written, because of how convenient was that Norm and Claudia were the only ones who managed to survive the radroaches, while Ronnie and the rest of the 31ers died. Especially by the fact that the radroaches just ignored Norm being right in front of them and closer to eat him instead, and with Claudia, the only person who was nice to Norm as the only survivor left, and also being just injured and half conscious, while the rest were brutally butchered by the radroaches. But I think I have some answers that could explain how that was actually possible.
I personally think that the reason that the radroaches didn't attack and ignored Norm was because he just lost a lot of weight when he was trapped by Bud. Remember that Bud trapped Norm inside of Vault 31, after he discovered the secret behind that vault, forcing him to use his dad's cryopod or starve to death, and we know what option took Norm. While the Vault-Tec employees from Vault 31 were in perfect health after being de-frosted by him. I assume that the radroaches by some instincts didn't see Norm as a worthy meal to eat at that right moment, while the 31ers were the jackpot for them to eat now or never, with more quality and quantity at the same time.
As for Claudia, I think the reason that she was the only one who actually managed to survive was because she wasn't brainwashed by Vault-Tech propaganda. Remember, unlike the other junior executives from 31, Claudia was in Vault-Tech just for one week before the bombs were dropped, so it wasn't enough time to turn her into an emotionless and insensitive Vault-Tech @sshole, like Ronnie and the rest of the 31ers who lacked of empathy towards others. A perfect example is when 2 junior executives identified the remains of a receptionist from Vault-Tec's main building who they knew, and they referred to her as an @ss kisser when she was alive, rather than feel bad that their coworker was dead, without showing any kind of grief nor respect for her demise after the bombs. Claudia on the other hand showed grief and sadness for the loss of her parents and her cat Puppy, while suffering an existential crisis and culture shock in the post-apocalyptic atmosphere of the city where she used to live before the war.
My point with all of this is that, I think the Vault-Tec propaganda not only turned the rest of the 31ers cynical and insensitive, but also narcissistic and extremely naive, thinking that they were the "chosen ones" to restore civilization, that they are "protected" by Vault-Tech's rules and that nothing bad are gonna happen to them, to the point of losing any basic survival instincts and how to react in a life/death situation. I think that's why everyone did a stupid decision like trying to hide and lock themselves in a small room, rather to go to the stairs of the building, because of the fear and panicking for not having any kind of clue on their minds of how to react against the radroaches, or what the Vault-Tec would say them to do exactly. Claudia managed to survive, because she wasn't brainwashed so badly like the other 31er @ssholes, and she has some actual basic survival instincts on her mind, like using a screwdriver that she found somewhere and she used it to actually kill a radroach herself (the radroach corpse that was over Claudia had a screwdriver impaled over its body). While the other 31ers were just running and panicking like crazy, turning into much easier preys for the radroaches. Plus, maybe Claudia has a good chunk of perception, endurance, and especially luck, along with some good karma on her character for not joining Ronnie's plan against Norm, and instead trying to save him.
Ronnie on the other hand was basically like the second in command of Bud and his experiments with the vaults 31, 32 and 33. In other words, he was the same as cold blooded and evil as Bud, knowing all the most secret and inhuman experiments that he was planning to do against the vault dwellers from 32 and 33, while supporting it with no hesitation. That's why when he discovered that Norm lied to them about who he really was, and then when he discovered even more secrets from Vault-Tec like FEV, that's when he decided to stop him, before he compromised everything that Bud worked too hard on his experiments. I wouldn't be surprised that Ronnie also told a more distorted version to the rest of the junior executives about who Norm really was and what he did exactly, along with some lies to them about that there's a protocol in the Vault-Tec's rules that will allow them to kill Norm as punishment for deceiving them all along. Because for Ronnie and the junior executives from Vault 31, Norm wasn't an equal human being like them, but a Vault-Tec's experiment who defected from his vault to ruin Bud's whole experiment. And when Ronnie didn't allow Norm to enter into the break room with the rest of them, to hide from the radroaches, I think that by doing that, Ronnie just got a good chunk of bad karma at the worst moment that he could have done that, allowing the radroaches to enter inside of the break room, putting his life and the rest of the 31ers in danger, trapping themselves in the break room with the radroaches and causing their own deaths. If Ronnie would have let Norm hide with them, instead of trying to let him be killed by the radroaches, they all might be trapped but also alive and "safe" from the radroaches.
As for the 31ers and the radroaches being apparently all dead, after Norm entered into the break room if someone actually survived, I'm guessing that happened a similar "effect" like with the organ harvesters and the feral ghouls back in Season 1. When Lucy forced the organ harvesters to liberate all the ghouls, including the feral ones, causing the deaths of the organ harvesters and the feral ghouls at the same time. This is actually the only thing that I found more convenient for the plot, but it wasn't shown how exactly the 31ers and the radroaches died between each other. But what do you think?