His idea presumes not that you can't scavenge newer technology, but that we can't replicate, repair, and manufacture more of it. Computers are built with computers. Advanced computers were built with less advanced ones. Sure, we can try to use some of what we found that survived, but will we be able to build manufacturing to build a modern processor with what we find that still works and the expertise we still have?
If we can't manufacture new smartphones, we need to have a baseline of computer to develop new computers that can eventually develop computers that can develop smartphones. Essentially he's proposing that if we lose our societal ability to compute advanced things, that we be able to fall back to the Z80 rather than the abacus.
Not sure I'm totally sold on it here, but it's an interesting topic to say the least.