This makes sense; for instance when you are 10 years of age, a year 
  represents 10% of your life, and seems like a very long time. However, 
  when you are 50 years old, one year has reduced to only 2% of your 
  life, and hence seems only one-fifth as long.

Interesting hypothesis, and he makes it look very scientific with the formulae and all, but it's still a wild crazy guess that delivers no actual falsifiable prediction. I think for claims of such magnitude, there should be a modicum of neurological or information-theoretical basis involved - instead we get to read repeated statements about how groundbreaking the idea is.

The article makes claims that at 30 life is essentially 3/4ths over which to me, while holding no subjective truth as far as I can tell, at least exhibit some self reference in the way that after three lines of statements the article's content seemed 75% over yet the actual text went on for much longer.

Subjectively time seems to go by faster the older we get, but that doesn't mean these bold claims are necessarily anywhere close to the truth. Personally, my relationship with time has certainly changed over the years, including the perception of a speed-up, but I also notice that some activities or states seem to last just as long (if not longer) subjectively as they did when I was 16.

My pet hypothesis is there are multiple factors involved in "the speedup", and that a large factor of it would actually be that our brains don't store repetitive events very well. This would mean as we get more experienced, an increasingly bigger amount of the average day consists of things we already did many times before so we don't store those moments in memory. That would result in increasingly large memory holes over time, which our brains then glance over as they piece together our past - thus resulting in an apparent speed up. This would also explain why days with unusual content seem to last much much longer than others (at least that's my experience).