He does join the conversation when Bingley is receiving Mrs. Bennett, to notice the confined circles in the country, and to question Elizabeth's assertion that poetry destroyed an admirer's affection for Jane. He asks Elizabeth if she has a desire to dance a reel. But for the most part you are correct, and even these examples show that it might be his inability to resist Elizabeth's verbal play that induces him to try. He also speaks slightingly of the Bennett's girls chances of marrying unasked. I wonder if the letter to his sister is only in answer to one she sent him? *chuckles*

And, yet, he speaks well, when he gives himself the trouble. He likes to contradict, but so does Elizabeth.