Kinda weird to just go for an argument of authority huh? I'd recommend watching the video for a non-authority based series of arguments based on multiple sources and a lot of data.

Anyway, the reason they wrote that paper is probably because they are talking about extreme hypotheticals themselves. Notice how their comparison is that it's twice as likely as a 2km asteroid impact, which are once in every few million year events. So we're still dealing with something extremely unlikely to occur in our lifetimes.