Why is the primary source for the Mitzvah to retell the Exodus on the night of Pesach, the verse of the "she'Eino Yode'a Lish'ol"? (If we examine the context in which each of these sons appears in the Torah, we find that are they aren't necessarily asking their questions on the night of Pesach!)

But we used this same verse above, in our answer to the Rasha! Why is the implied rebuke to the Rasha included here, in our response to the fourth son, the "she'Eino Yode'a Lish'ol"?

What is meant by "not knowing to ask"? Why might the "she'Eino Yode'a Lish'ol" deserve to get the rebuke of the Rasha?