I'll put down money that this article ends up having it backwards when people are actually playing next gen games. I don't care if my console gets warm if it's basically silent. The x1x gets warm but it's SILENT and on the other hand my pro gets hot and is noisy as all hell and so was my ps4.
So my bet it the ps5 gets hot and noisy when playing ps5 games and the Xbox series x will stay the same temp a few (and it's only a few out of like a hundred) when playing next gen games but it will remain silent.
Just looking at the way the hardware is laid out in the Xbox and how it handles cooling is the basis of my guess. Since sony is being coy with allowing lots of people to use preview hardware unlike Microsoft it's hard to say but I do know the ps5 doesn't have the split motherboard design which would make cooling quietly more difficult.
Either way if they both make noise then...it is what it is. The Xbox is essentially like a PC with a 2080ti and the ps5 is essentially the same but with a 2060 super.