Hi agsIn,
Domain authority has a ton of other factors beyond just domain age. Rand Fishkin from Moz actually did a great video on it, but for some reason, the videos aren't accessible right now, maybe someone from Moz can check on them? It'll be great to take a look at those videos again.
http://moz.com/blog/whiteboard-friday-domain-authority-page-authority-metrics
Also, I took a look at the site you mentioned, and though it was registered back in 1996 (which is really old), its backlink profile isn't fantastic and includes quite a few backlinks from link exchanges and pay-for-links directories. I think it would be a good idea to take a look at this infographic: http://searchengineland.com/seotable/
I use it as a constant reference point for optimizing a site and it was great for helping me learn more about optimizing sites in general too.
Hope this helps!