He does seem like a bit of a "character." But maybe he had a webscraper that just happened to catch the premature post, and is just trying to self-aggrandize on a real scoop? Nasawatch [0] is saying that several sources have confirmed it to them...
Probably a leak from one of the embargoed reporters is more likely, if it's true. Obviously we'll find out soon. But if the Earthsky.org story a fake, he certainly did a vastly better job producing the fake than he did self aggrandizing off of it.
It seems to be His Thing and he has been looking at the preprint of the paper since a month ago. There are people outside the normal academic framework who are knowledgeable and even influential within a specialist field.
[0]: http://nasawatch.com/archives/2020/09/phosphine-detec.html