This doesn't seem to include text from submissions.

I ran it on Brian Armstrong's temp account from here, and it said it didn't write 10,000 characters:

https://news.ycombinator.com/item?id=3754664

EDIT: Or maybe it's something else because Brian only wrote less than 6k characters. But then why can my account be looked up?

Also, I would guess quoted replies are included, which muddies the analysis. Seems to be a very naive implementation. Much more can be done, but this was probably just a quick project.