Questions, Yes. Contempt, No.

It shall be that when your children say to you tomorrow, “What is this service to you?” You shall say, “It is a Pesach feast-offering to Hashem, Who passed over the houses of the Children of Israel when he smote the Egyptians” (12:26-27)

According to the Haggadah, this is the question posed by the “wicked son”. However, whereas the Torah gives this response shown in the Pesukim above, the Haggadah makes no mention of this. Rather, it says to rebuff him with a statement “Had you been in Egypt, you would not have been delivered.”

If you look at the wording of the Pesukim (13:14), it says “and it shall be when your son will ask you tomorrow, “What is this?” you shall say to him, “with a strong hand Hashem removed us from Egypt”.

"...כי ישאלך בנך מחר לאמר מה זאת ואמרת אליו"

The Pasuk does not say “when your children will say to you” but when “your children will ask you”, it also does not say “you shall say” rather “you shall say to him”.

A question deserves an answer. The wicked son is not asking a question; he is making a statement. In a jeering manner he is saying, not asking, “Of what use is this ancient, obsolete ritual to you anyway”. He is not interested in an answer, so there is no point in giving him one. Shlomo Hamelech says:

(It is possible to skip out this bit and still sort of understand the Dvar, I say sort of because R'Hirsch’s eloquence explains the concepts amazingly well - better than I do later on)
(If you are skipping out - look at the middle Mishlei quote, (18:2) that pasuk is needed)

If you just let me quote a couple of Pesukim here:

לא יאהב לץ הוכח לו
אל חכמים לא ילך
“A scoffer does not like to be reproved;
He will not go to the wise.”
לא יחפץ כסיל בתבונה
כי אם בהתגלות לבו
“A conceited fool has no desire for understanding;
but only wants to express his own view.”
למה זה מכיר ביד כסיל
לקנות חכמה ולב אין
“What good are the means in the hand of the conceited fool
To purchase wisdom, when his heart is not in it.”

(15:12), (18:2), (17:16)

R’Hirsch say something on here on these Pesukim if you let me , I will just quote straight from the Sefer - His meaning is articulated much better than I could if I was paraphrasing:

Two characters according to Mishlei, will hardly succeed in gaining wisdom: Letzim and K’sillim. For the letz everything which transcends the concrete and the sensual is fantasy: whatever is ethical, holy, relating to Hashem, is the target of his ridicule. A doctrine which demands sacrificing palpable, sensual advantages and pleasures for ethical ideals, seems to him an absurd pretension and the followers of such a doctrine who find serenity and happiness in its fulfilment , appear to him as laughable fools.

Yet all this is only on the surface of the man. No matter how able a demagogue he may be in the circle of an attentive audience by indulging in contemptuous irony, deadening every feeling of reverence in the hearts of his companions, his own confidence is not quite so firmly established. He is afraid that some day he may be taught better, and therefore he fears, indeed hates, to be reproved.

Another, perhaps even larger, group of people who are usually lost to wisdom are the K’sillim. A K’sil may posses a good mind. He may even have had some education. However, he is so pleased with his own mental faculties and his smattering of learning that he is convinced of the absolute infallibility of his own views. Such people have not the slightest doubt that by themselves they are able to form a judgement, and have no need for further instruction that anyone, let alone from a higher authority. While a person of insight is aware of the limits of his knowledge and of human intelligence in general, a prideful K’sil is fully satisfied with his own unwisdom; he never even tries to learn the facts. The only thing he is interested in is to ‘sell’ his own opinion, which to him is the highest, most irrefutable one. His heart is so completely filled with his own vain pride that there is no room left for anyone else.

However when there are scoffers around who depreciate the Torah, you should reinforce your own views and say, to one another “it is a Pesach offering to Hashem”.

The author of the Haggadah analyzed the text of the Torah carefully, and his interpretation teaches us not to get involved in a discussion with someone who is not interested in learning, but is merely provocative. Also, when there are threats to our principles, we should stand together in mutual reinforcement of our beliefs.

Shabbat Shalom,

eli :)

There are many more things to say on this, and I will B"zh comment/edit the post for those who wish to read it. 

The extra ideas should tie in the two varying concepts of Letz and K'sil so both are expressively evident in the wicked son's question and I will also say over a Dvar Torah I heard today from Gavriel Rosen on why it says  כי ישאלך בנך מחר - concerning the wise son and not by the wicked son in the Haggadah.