This is both a difficult and interesting question. It's difficult because of the wording you use. (The question is about The Bunker Diary, yet we are asked to focus on two other novels.) Further, this is such an interesting question because, even though The Bunker Diary is "technically" considered children's literature (as it is a "young adult novel"), there is no way we would be reading it in a third grade classroom. Treasure Island and Swallows and Amazons follow both history AND tradition of children's literature. I would have to say that The Bunker Diary fits into NEITHER history NOR tradition of children's literature; however, it breaks new ground in a new category.
In regards to the "history" of children's literature, I agree with most scholars that say it should be "literature designed to convey the values, attitudes, and information necessary for children within their cultures." Being young is about having adventures to get a child ready for the adventures of life. In this way, that is often the history of children's literature. That is so with Treasure Island and Swallows and Amazons. Both of these stories focus on both bravery and adventure. Bravery, of course, is an admirable quality, and one quite appropriate to teach children. In Treasure Island that is certainly true of Jim Hawkins as he defeats the "evil" pirates and finds the treasure and Swallows and Amazons, set in the more "modern" time of the 1930s is almost a reenactment of Treasure Island as the children from the Lake District "fight" pirates and "search" for treasure. Bravery is always both noted and admired.
Here enters The Bunker Diary into the "history" of children's literature in an incredibly modern setting. I am going to admit here that there is some relevance of bravery here in the character of Linus. Linus, of course, is always trying to get the group who has been kidnapped to work together in the effort to escape. The problem is, when talking about bravery to children who, most of the time, we are trying to stress the positive aspects of the world they live in, The Bunker Diary bravery has no good result. Not only does Linus die in mid sentence, but EVERYONE dies, ... bravery or not.
Tip for the day: never eat a bible when you're starving to death.
Critics of the book point to its inherent nihilism (the idea that the world is coming to nothing and that values are meaningless). I suppose if one believes nihilism is true, then this book is truly didactic. However, most of us who do NOT, truly do NOT want nihilism taught to our children. Why would we not consider this children's literature, then, historically? Because it doesn't teach values GENERAL TO our culture. It stresses the values from the fringes of our society.
In regards to tradition, it is often focused on fantasy (such as The Wizard of Oz or Treasure Island) or focused on adventure (Such as Swallows and Amazons or the Nancy Drew Mysteries) or BOTH (as in the case of Harry Potter or The Chronicles of Narnia) or focused on didacticism (such as Aesop's Fables). Fortunately or unfortunately, The Bunker Diary is as realistic as you can get. This leads nicely towards the nihilism it teaches. It is NOTHING like the traditional children's literature mentioned above. There is no fantasy. The adventure isn't adventure as much as it's the horrors of kidnapping. Yes, it teaches bravery, but it teaches that bravery is of no use.
Thus, The Bunker Diary belongs in its own, new category of literature: Dystopian Children's Literature. Don't bother looking it up. I coined the term myself. A dystopia (a disfuntional, corrupt soceity) is the exact opposite of a utopia (the perfect society of harmony and peace). In short, it makes me cringe to put The Bunker Diary in to the same category as Charlotte's Web. And, for some reason, I don't have as much of an issue with calling it "young adult literature." I feel the same way about The Hunger Games. Some serious, violent issues are dealt with here: issues that we MAY want to PROTECT our children from as long as we can. Once they get to be young adults, perhaps they can hack it. However, even then, some can't. If they'd like to read a tried-and-true story where everyone dies, I'd suggest reading a young adult version of Hamlet.