Yes, it works the same way even for content Google indexed at publication time. For example, here are chatgpt.com links that Google displays as being from 2010-2020, a period when Google existed but ChatGPT did not:

https://www.google.com/search?q=site%3Achatgpt.com&tbs=cdr%3...

So it looks like Google uses inferred dates over its own indexing timestamps, even for recently crawled pages from domains that didn't exist during the claimed date range.