Want to get a geek roiled up? Tell them you develop code in proportional fonts. The comments on that article are a text book example of irrational geek argument try to get the higher ground.
Remember, there is one wholely optimal way to develop code, just like there is only one best editor, and only one best programming language. Your decision of best would in no way be defined by the preferences of the skilled people you looked up to when you first learned this whole software development thing.
For the record, I prefer Arial.