This seems like an uncharitable take. Personally I would refrain from putting a 20 year barrier around the qualification, that seems a little harsh.
TFA's take makes sense in a certain context. Getting a high-quality design which is flexible in desirable ways is now easier than ever. As the human asking an LLM for the design, maybe you shouldn't be claiming to have "designed" it, though.
I was specific to the age of the product not of the age of the developer on that project. The point is that "high quality design" is such a fleeting thing that perhaps "longevity of design" is more worth having. It's also probably the case that the latter is much harder to come by which makes it a perfect barrier of qualification.