Agreed. In addition to sounding like spitballing, even the linked articles (from what I saw) don't show a clear way in which the former employee came to 70%. Overall this article comes across as fear-mongering but one of the linked sources was an interesting blog post (IMO) about why people should _stop_ providing specific estimations of p(doom).
https://www.lesswrong.com/posts/EwyviSHWrQcvicsry/stop-talki...