Wouldn't doubt it, but I didn't use his essays for training, just his tweets.

I'm really impressed with how well it was able to place PG on the political spectrum and capture his world view.

They are curated. Probably around 5% of the generated content was usable. As someone who has been responsible for coming up with content for twitter accounts I can say even with having to curate the results it was still orders of magnitude faster than having to write original content. It took around 4 hours to generate about 3 months of Twitter content.