It is likely that Claude enabled this, given:
So, I put the notebook with that design in it on a shelf.
For nearly 20 years.
Today, I’m happy to say that I’ve finally been able to carve out enough time to grab that “old” redesign, flesh it out further, modernize it, and make that dream a reality.
Hmm, what could have allowed the sudden burst of productivity? /s
That said, we shouldn't assume that if he used an LLM we know what quality the finished product is.
For all we know, he used an LLM to get a working rough version, and then rewrote every method, bit by bit. For this sort of product - an decades-old app that can result in data loss and so the wrath of furious users - it is more likely the developer was prudent.