He merely suggested a small fee though. 5.1% per year and only on cash, not some CDBC with privacy concerns. If you keep your money on savings accounts you wouldn't pay anything. If the economy is growing you would get paid interest. If the economy is declining you might pay negative interest.
This is different from a coupon that expires instantly. That is a terrible idea. Don't do this.
Also, the idea of demurrage currencies is to replace the devaluation via inflation with a nominal fee so it is possible that in countries with high inflation rates, the new currency would end up losing less value over time simply because it maintains price stability easily.
Edit: btw. His theory is dated in the sense that Keynes and Dieter Suhr have an updated interpretation. With a hint of Fisher Black you are going to get one of the most interesting economic theories that can explain most of the suffering in the world based on very few assumptions. The money and land reform policy proposals still remain relevant today.
