Why does Rikki-Tikki answer Chuchundra scornfully in "Rikki-tikki-tavi"?

Rikki is scornful of Chuchundra because he is a coward and wasting Rikki’s time.

Riki-tikki-tavi is very brave.  Bravery is a trait of mongooses, apparently.  Even when he faces extreme danger, Rikki is never afraid for long.  His most common emotion is curiosity.

There is plenty of danger in the bungalow and surrounding gardens.  There is a family of cobras, and cobras are the natural enemy of the mongoose.  The cobras, Nag and Nagaina, target...

Rikki is scornful of Chuchundra because he is a coward and wasting Rikki’s time.

Riki-tikki-tavi is very brave.  Bravery is a trait of mongooses, apparently.  Even when he faces extreme danger, Rikki is never afraid for long.  His most common emotion is curiosity.

There is plenty of danger in the bungalow and surrounding gardens.  There is a family of cobras, and cobras are the natural enemy of the mongoose.  The cobras, Nag and Nagaina, target the family of humans in order to try to control Rikki.  The snakes are very afraid of Rikki. 

Chuchundra the muskrat is so fearful that he skulks around the edges of the room instead of coming out into it.  Even though he knows something about where Nag is, he is afraid to get involved.  This annoys Rikki, who needs the information and does not understand the muskrat’s fear.

Chuchundra sat down and cried till the tears rolled off his whiskers. ``I am a very poor man,'' he sobbed. "I never had spirit enough to run out into the middle of the room. H'sh! I musn't tell you anything. Can't you hear, Rikki-tikki?''

Rikki threatens to bite Chuchundra, not to be mean, but because he needs the information quickly and Chuchundra is taking too long.  Rikki is not in a sympathetic mood.  As far as he knows, the snake could attack the family while he is standing around trying to get information out of the muskrat.

Chuchundra tells Rikki that he should have talked to his cousin, Chua the rat, because he feels that Chua would have more information and be more forthcoming.  It is too late though.  Chuchundra tells Rikki to listen.

``That's Nag or Nagaina,'' he said to himself; ``and he is crawling into the bath-room sluice. You're right Chuchundra; I should have talked to Chua.''

In the end, Rikki is able to take care of both Nag and Nagaina without anyone getting hurt.  We are told in the beginning of the story that Chuchundra gave Rikki advice, and he did.  Even though Rikki had no patience for the muskrat, he was able to telling Rikki where the snakes were hiding.