Eternity is longer than I want to keep fuel. In fact, I'm thinking in another 30 or 40 years, tops....I'm outta here. Shovin' up them daisies.
There is a flaw in their thinking, though. Diesel usually has enough water in it that bacteria can grow, even if you can make sure no more ever gets in. So sealing the storage container, while it would prevent any more water from getting in, won't do anything about the water that already exists. Plus, your container wouldn't be vented, which is not a good idea if temperature is going to vary much.
I store my diesel fuel at the gas station. Let them keep the stuff. I'm in town often enough, and the Kubota burns little enough, that I can just get some when I'm at the station filling the truck or my pie-hole.