When I clicked the article itself, this is one of the interesting links I found. The ages are based on organic metter found in the tunnels.
Except, there doesn't appear to be any serious documentation of the "find".
Your link says:
The date of 29,000 years was obtained from a piece of organic material retrieved from a clay layer inside the outer casing to the pyramid which underwent radiocarbon dating. It follows a sample date obtained during the 2012 dig season on material located above the concrete at 24,800 years.The "casing" is naturally occurring stone. Finding naturally occurring organic material on a naturally occuring hill/small mountain, is not particularly unusual.
It is pretty easy to determine if something is manmade. The signatures are obvious.
When you have to use the latest technologies to claim something is not a natural formation, you are grasping at straws, attempting to wring evidence from nothing.
There are several volcanic hills near me in Arizona, that have a pyramid look to them. The pyramid shape is a naturally stable one.