One interesting interpretation of these stories would be that, although technically, Seymour is still alive during the first story, that both stories could be viewed in light of Seymour's suicide. Then, Seymour's failure to appear at his own wedding would become a metaphor for his suicide where he chose not to show up to his life anymore. They are similar rejections, and therefore, the conversation with the wedding party is more like an argument against those who would judge Seymour for being depressed and choosing suicide.
When we get to the titular line in the story, it comes in the form of a friendly, encouraging note from Boo Boo to Seymour. She writes on their shared bathroom mirror: "Raise high the roof beam, carpenters. Like Ares comes the bridegroom/ taller than a tall man." This line comes from Sappho the Greek poet, but Boo Boo uses it as a blessing on Seymour's wedding day, suggesting that to her, he is an epic hero. This is similar to Buddy's experience of Seymour, and it helps to frame Buddy's defense of Seymour's character.
It's as if Buddy is saying, "You who judge the depressed and suicidal: If you had any empathy at all, you'd see what a bold, courageous person this was, and how much they really contributed." This is a defense from one fictional character about another fictional character, which is important, because seeing the characters as literary devices, the reader will also see that J.D. Salinger himself is offering a defense of those who don't survive their mental illnesses.
