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).
The article mentions supporting multiple favicon sizes and old browsers. Did you even read the article or was it too hard to read on your low dpi display?