Exactly what does it explain ??
The United States has far and away the largest gold reserves in the world.
Basically, only conspiricy nuts and people wishing to drive-up the price of gold actually believe otherwise.
The source you linked has zero proof of its claims...zero.
But what if it was true and the United States had no more gold left??
It would be basically meaningless.
The United States has been off the gold standard for almost 45 years. The strength of the dollar and of US Treasuries is not based on gold. It is based on the fact that the United States has the largest and deepest and most resilient economy on the planet...and this by a wide margin. Consider that the United States has over twice the GDP of China but less than 1/4th of China's population !!
If your concern is that the influx of "secret" reserves of US gold have been seeping into the market and depressing the price of gold...well, OK, you are entilted to that opinion.
I have a more logical explanation: the price of gold has been artificially high for a number of years due to market speculation.
Step back and take a look at the firms who relentlessly advertise gold as a "great investment".
Why do they do this?? Because they make money when gold is bought and sold, regardless of whether the gold investors actually make money or not.
Gold can be a good investment, for sure. Especially if you buy low and sell high...LOL...But the gold market is volitile and highly speculative...in short, at most it should be a very small part of a balanced portfolio. I actually think most financial planners would advise staying away from it completely.