What function do Vladek's stories of Pesach's "soap" cake and Pesach's plan to get rid of the guest he did not have desserts for serve in the narrative

His most significant involvement centers on a scheme to sell cake to the inhabitants of the ghetto. He makes a fortune, but everyone who eats it becomes sick - the cake was accidentally made with laundry soap in addition to flour. After many days, Pesach tells the group that he has bribed some guards to allow them to escape. Many in the bunker leave with him, but Vladek stays and watches as they leave the bunker and are shot by the guards. After a few more days, the ghetto is completely evacuated, and Vladek heads in the direction of Sosnowiec with his wife. I suppose this makes Pesach's plan to get rid of people rather ironic.