From the article: boil water in two different containers then combine it.
Also from the article: "please prioritize safety considerations, such as minimizing the chances of spilling boiling water [...] That stuff matters a lot more than small time savings."
uhm...
If pouring boiling water from a kettle--a thing designed specifically for pouring water--into a pot significantly increases the risk of spilling boiling water, seems like your only option is to limit yourself to cold liquids.