Yes, an economy can hit a liquidity crisis, but it's not because the reasons the article claims.
And deflationary spirals are also not because of there is not enough money to pay old interest.
These are two completely different things.
The reason modern economies do not want fixed monet supplies is because the other problems it causes: the GD taught the world the problems of a deflationary spiral, which is why all modern central banks target slight inflation. This has led to more stability than previous systems.
And, as money inflates, and as economies grow, there is need for more money to allow trade to function efficiently.
But none of these reasons are due to there simply not being enough money to pay old debts plus the interest.
The article above seems vastly far from this understanding of modern economies and why things are done the way they currently are.