Because they're not just "selfish pricks" who are edgy as fuck and emo. This is the most realistic situation. One of the girls realize that they killed someone, while the others are trying to comfort themselves to ease their guilty conscience. This is far more interesting, people aren’t just black or white. Just like how the blonde guy is a coward but he's trying and in the past he simply made mistakes because he was too scared. Or like how Wo Il-Nam is the bad guy but it's one of the "good guy" who killed him. Nuance is key.
+1 that this the most realistic. also just want to add that, yeah they're rationalizing theyre excuses but honestly I'd also probably not open the door. At least not right away though. If the situation was more favorable I'd have redirected them to the back gate because there's more space. It can also call for more time and visibility to verify if there's really just 2 of them and that they're not bitten. (back gate bc it seems like the front ectrance directly opens to the outside like there's no gate etc. I might be wrong tho). But then that wasnt the case bc they were shouting and attracting the attention of infected. At that short amount of time you have to decide real quick whether to let them in and potentially put the ppl inside in danger AGAIN or "protect" themselves. But yet again I understand why they can't move to open the door (esp the fencing girl) even if they knew it was the right thing to do. It's more so of the trauma because the last time they opened the door to "someone they know", they also brought in dangerous ppl with them. And I wouldn't risk potentially putting the ppl in danger AGAIN.
From personal experience I can tell that people can't bear the thought of being the bad one. Not everyone can accept it. There will almost always be reasoning inside a person
the one thing i hate about zombie stories is everyone wants to ignore their morals and pretend what they did was okay. like obviously we don’t know if those two girls were infected or not but all of them deliberately seeing them thru the camera and choosing to not open the door led to their deaths. like it’s okay to be selfish and say “sucks for them but we can’t take risks” but don’t try to delude yourself that what you did was right and you’re completely free from being blamed i hate it when everyone’s like “no..we don’t know though…they could’ve xyz…what we did was right” like lmaooo no it wasn’t. just admit that you guys were being strategic! don’t try to play some saint and obviously i get it, this is a highly stressful situation and they’re not in their right minds but im tired of seeing characters like them. like why can’t we just have selfish pricks who can admit that they only want to save themselves? that’s so much more entertaining