As others have said, I was once painfully shy myself. And there is one thing I can tell you for sure: the last thing a truly shy person would have is the nerve to make the kind of remarks such as Darcy makes in public (even if they are upset). You would rather have a hole open up in the floor and swallow you first. You never make scenes, or want to do or say anything that would bring attention to yourself, or cause negative comments about youself---you bascially just want to quietly blend in with everyone. And with shyness in the distant past, there must be some residue, because even now I am mortified to imagine saying such things in public. Strangely enough though:

When I first came to Permberley, I actually leaned toward believing that Darcy was shy. But after particpating in group reads for nine or ten years, reading and discussing JA's works and letters I think it opened the way for me to change my opinion in some areas. Not only that, one day it sudddenly occurred to me that, hey, I was once shy and no way could I have even have thought of making such comments. Every time I read P&P and I feel even the smallest desire to give any leeway to Darcy due to his behavior at the Meryton assembly (even the teensiest of bits), those words that come directly out of Darcy's mouth pull me back. No, in my opinion, it takes a haughty person who thinks he is above those in his presence to manage this, not a shy one. But it does help me to relate to anyone who prefers to believe that Darcy is shy because I was once in the same boat myself. :)