More evidence: the user posted three well-formatted multi-sentence comments within 15 seconds.

https://news.ycombinator.com/item?id=47110801 (13:23:08)

https://news.ycombinator.com/item?id=47110803 (13:23:15)

https://news.ycombinator.com/item?id=47110804 (13:23:23)