Two things: I really wouldn't be comfortable with a Twitter auth being set up. I have a Twitter account, and currently don't use it, but for the past two years I didn't have a Twitter account.
Knowing what I do about DN and taking into consideration how it's helped me, I would have been very upset if I were forced to use Twitter to log in, thus not being able to create an account.
I know I'm in the extreme minority, but I don't think we should essentially say that to be a designer you must have a Twitter account.
Also, While I was reading Kelly's response to Pasquale, I had an idea. What if there were some sort of pre-Recent and/or pre-Top stories area where all new links had to go, and recognized good users (i.e. ones with lots of rep) can filter and vote on which ones should not be published to Recent or Top.
To vote against a story being published to Recent or Top, the person has to give a explanation of 140 characters or more explaining their reasoning. People who are obviously trying to game the system will be easily recognized by the team, which will be much easier to manage than without this system.See also: