It's just a bit of temporary[1] redundant local infrastructure that is hopefully never used at all, and when it is used it won't be used for very long. The fuel will remain available for as long as any of us reading this are alive.

The price of the fuel may go up (it probably will go up), but it doesn't really matter much at this scale whether it costs $25 per day to run or $100 instead -- the power grid will come back online soon enough.

[1]: It's a backup generator, not an heirloom. In 50 years, people will look at that old thing and laugh at how interesting its archaic nature is. They might tinker with it. They might give up and have Jeb haul it off as scrap. And that's all fine, too.