Sorry about that – the point of the article definitely wasn't to exclude non-Retina users, it was just to document what I was encountering when I came to creating a favicon for the site.
You don't think screen resolutions will continue to increase? I give it a couple of years, maybe less, before the "retina" resolution is standard hardware.
That's most likely going to be a >200dpi screen, where you can simply use 2x upscaling for better performance (with no visual degradation compared to current monitors).