As the author themselves admits, this requires a very narrow band of Goldilocks catastrophe. Not catastrophic enough that you still have electricity, but catastrophic enough that all the plants on this list are destroyed or rendered unusable or embargoed from you? https://en.wikipedia.org/wiki/List_of_semiconductor_fabricat...
How is that going to work exactly?
No, it's a fantasy disaster, like Day of the Triffids and all the other John Wyndham style "cozy catastrophe" novels.
Real catastrophe is slow and grinding. Think "decline and fall of the Roman Empire" - a multi-lifetime process. Or something like Venezuela, where crumbling power infrastructure took out their aluminium smelter. This causes it to freeze solid and is unrecoverable without rebuilding the crucibles.
All the fabs on your list are fairly modern, and it is easy to see how they would be impossible to maintain in a Tainter-style collapse.
I would be looking into what you can do with ~1 um processes, which are currently accessible to amateurs. E.g. designs like https://news.ycombinator.com/item?id=11720289