Usually the writer goes to great pains to make a show of basing points on hard numbers --but only when it doesn't matter because he's just rambling. On this debt thing (the nub of the entire rant) he suddenly flips into fantasy mode making up numbers knowing the true believers never care about checking.
Seriously, in the real world we got the US --with maybe a fourth of the world's wealth-- at $79T assets minus $13T debt and that = $66T net worth. Money is important and we can't just make up our numbers and think we can get away with it..
There's a category error in your formula.
You have government debt minus national wealth.
As if the government was the same as the nation.